Actually I liked the time traveling sorceress thing, because if you paid attention to what was happening in Laguna's Winhill and Eshtar (however you spell it) dreams and then with Squall's time, Ultimecia's point of being in the game makes sense. She pissed off because Seed and the world hate her kind and she knew about the legendary Seed who was supposed to come and take her life. So she desires time compress in order to escape death.
Dr Odine and sorceress Adel during her reign were looking for a way to identify the sorceress gene in people, that's why Adel was kidnapping children in the first place and why Ellone was of interest to her. She kidnapped Ellone so Laguna went to save her and managed to free Eshtar at the same time. That's also kind of the point like while Ellone is searching for her answers, we see what happened with Squall's origins but also what was going to cause the future problem in Squall's time.
Because while Adel was sealed in the tomb and shot into space, Odine obviously was continuing his research into the sorceress gene. And he managed to identify it, which we know because he determines Rinoa is a sorceress, the people tell Squall over the radio that she is one during the Ragnarok 'eyes on me' scene. So what do we know
1) Adel was looking to locate and identify the sorceress gene, she kidnapped children to do so.
2) Odine between then and now (which we know from in game is 17 years difference) has successfully identified it by Squall's time, because we find out Rinoa is a sorceress from Eshtar officials.
3) Ultimecia is from a future time many generations apart from Squall's own. (which are Dr Odine's own words) in which case technology would have advanced considerably by her time. And yet the ability to locate the sorceress gene is identified in Squall's period.
Then there is her Deling City speeches (both English and Japanese which are entirely different by the way, the Japanese one is far more revealing of her true feelings about humanity and her intentions. So English first
'Lowlifes. Shameless filthy wretches. How you celebrate my ascension with such joy. Hailing the very one whom you have condemned for generations. Have you no shame? What happened to the evil, ruthless sorceress from your fantasies ? The cold-blooded tyrant that slaughtered countless men and destroyed many nations ? Where is she now? She stands before your very eyes to become your new ruler.". "This is reality. No one can help you. Sit back and enjoy the show."
(And her Japanese one)
"......It reeks. Filthy fools. Since time immemorial, we witches have lived within illusion.
The foolish fantasy you produced. Adorning their bodies in dreadful costumes, the witches who curse virtuous humans by means of cruel rituals. The terrible witch who burns your green fields and freezes your warm homes with ruthless magic......Worthless.
Now that the witch from the illusion is come to be seen as a friend of Galbadia, you sigh in relief? Who is dreaming fantasy after fantasy?" "Reality is not at all gentle. That being the case, you fools! There is nothing for you but this!" (when she kills deling)
"Escape into your own fantasies! I shall continue to dance for your world of illusions!
I shall dance for eternity as the witch who brings you dread! You and I. Together, we shall create the final fantasy. Within are life and death and sweet dreams. The witch travels toward the eternal illusion! The witch and Galbadia on to eternity!"]
So I think Ultimecia's role in the game is entirely justified and reason is given for it. It probably would have made more sense however if we were aware of the prophecy earlier in the game. But Ultimecia does mention it at Galbadia Garden whilst possessing Edea 'So the time has come. You are the legendary Seed destined to face me' and Squall says 'What is she talking about'.
I really think the mistake Square made was not not focusing on Ultimecia being present and revealing her on disk 2 rather than 3 because it felt rushed in how we were told about her.
Instead of the stupid garden factions, missile base stuff we should have gotten straight back to Edea and had a few more encounters with her and Seifer and they could maybe reveal Edea and Cid being married in another way. You know ffVI you couldn't go an like an hour and a half after Kefka was introduced without really hearing his stupid laugh or some reference being made to his involvement in the goings on in-game. That's what Ultimecia was missing in my opinion to really kind of establish her place in the game. Though I do get they needed the missile thing in order to go to Trabia and find out everyone was from the same Orphanage, but they should have scrapped them growing up together.
It took up so much unnecessary time in order to explain how the party knew one another instead of on the villains motivation. Because once you know Ultimecia is actually there causing all of the stuff from the start of the game. Her role becomes larger but her name is just thrown out there on disc 3 and it's sudden to mention her, and she feels very last minute. Yet the plot-line for Ultimecia to even be in the game is spread throughout the dreams and Squall's storyline so that was a mistake. They should have cut the missile base, garden and trabia and made them focus on the villains and all the stuff to do with them, Edea and Seifer more encounters with them, continue the love story a bit more yada yada the party members become more familiar with each other, they grow to like each other more team bonding yay.
Then gone after Edea doing that plotline revealed Utimecia, then the rinoa coma outer space thing, we should get the additional party members stuff on disc 3 then of course you have the saving Eshtar thing and Lunatic Pandora etc. The party should have just come from different places and have banded together as a team of Seed, because despite all being different they are from a Military academy and much like the Turks should bond and build up their trust of one another especially with Squall given his attitude, and had them be established as a team who will get the job done, and are like family through all of their experiences together rather than all being from the same orphanage. Thats what I think anyway
And then disc 4 should have been the whole revealing of the plan to stop Ultimecia, and then doing all of the usual final preparations, then fighting Adel and Seifer a final time and then going to the future. Plus you could have done additional stuff like seen the towns generations later. I think they had 4 discs and they should have cut some of the plotlines they had in order to keep the game from seeming confusing or rushed and choppy in places.
Truthfully, I really liked VIII. Like a lot of the FFs (X-2 comes to mind), I felt like some things could've been done better.
Looking on it now, I've realized that VIII and IX's graphics always seemed really kind of... not good. Like so much detail was attempted to be crammed into the textures that it seems really messy.
All of the Playstation era FFs, at least to me, could do with a remake of some sort, where the textures are actually decent. Not necessarily voice acted, or things retconned (that's a big problem I have with the Compilation), but just... nicer looking.