The problem is that, aside from graphically(at the time), there was nothing interesting about Final Fantasy 7. It's better than 8, sure, but revolutionary? Revitalized the genre? Those are some bold statements. Especially considering Final Fantasy 7 was a damn near straight rip of the systems and even the story found in the direct previous series installment, Final Fantasy 6.
Both games use magic rocks to power up your characters (materia and espers).
Both games feature the atb combat.
Both games feature characters with their own abilities independent of magic etc. Although in 6 you didn't need to fuck around with filling up a limit bar to use a characters unique attack.
Both games feature a mandatory battle with Ultima Weapon (Atma in the original SNES translation)
Both games feature an impending cataclysmic event that will bestow great power upon one individual (at least Kefka was slightly more successful than Sephiroth)
Both games feature a theme of nature vs machine. In 6, its the Emperors desire to harvest the Espers in order to make a magi-tech empire; in 7, its Shinras desire to harvest the lifestream in order to... build a magi-tech empire. Both of these organizations are searching for a "holy land" - in 7, Shinra seeks the Promised Land; in 6, Emperor Gestahl seeks the land of the Espers; both to similar ends.
Both games see the primary antagonist cast away near the finish line for a shadow antagonist. I.E. neither Kefka nor Sephiroth have have any direct interest in the PC's till towards the end of the game.
I'm not saying that FF7 == FF6; just pointing out some very obvious similarities.
As far as why 8 is such a piece of trash, well:
FF8 was one of the dumbest fucking games I've ever played. Seriously the most retarded "plot twist" I've ever encountered, even by Japanese writing standards. Level scaling? Emo characters? Spell drawing? Just terrible. Anyone arguing it was better than 7 which basically revitalized the entire genre is beyond help. There is shit taste, then there are people who praise FF8 and call masterpieces like Arcanum bad. Get out.
This pretty much says it. If I had to elaborate though, I supposed I would list off FF8s failings as follows:
1. Squall. Squall is a horrible main character, and like most of the side characters in this game, he can be largely characterized by his personality. Squall is the angst
and nothing else. A lot like how Zell is the loud obnoxious one
and nothing else. The characters in this game are largely forgettable, and nothing meaningful ever happens with or to any of them. Sure, we find out at some point that they all grew up together in an orphanage (minus Rinoa) but the game does absolutely fuck all with this revelation.
2. Speaking of Rinoa, and how her and Squall have such an enchanting love story, maybe you oughta go and watch Grease first. In one particular scene when the party thinks Seifer has been executed, Rinoa heavily implies that her and Seifer shared some Summer Nights magic. In other words, remember the opening scene to FF8 where Squall and Seifer are crossing swords? Yeah, I'll leave that as it is.
3. Ultimecia. Who?! Yeah, just, fuck. If I need to tell you whats wrong with Ultimecia, then you're probably just never going to get it. Ultimecia is dumb cause she's an act three shoe-horn for a final boss. Imagine another, better game, if it pulled some shit like this. Imagine FF6, if you've just beaten Kefka, but all of a sudden everyone starts talking about, "Oh, uh, we gotta go to the end of time or something and fight John. Don't ask why, just shut up, dick."
4. Nojima. They let Nojima design this abomination. It isn't unheard of to promote other writers and even developers to the level of lead designer, but Nojimas only other noteworthy work prior to this was telling Sakaguchi that killing Aeris in FF7 was a pretty good idea. *sigh* Nojima would later go on to be a lead designer and co-founder of Nova Fabula Crysta-agh, it hurts. He would later go on to make the FF13 trilogy. The guy is hot garbage as a writer is what I'm saying.
5. Everything about its combat system and design. Holy fuck, you spend more time in menus in this game than anything else. Swapping magic charges, Gfs, junctions, using abilities to create items from cards to use those to make magic, using lesser magic to turn into higher magic. And then we have the damn Draw command. Followed closely by level scaling. Gross. Not to mention, every playthrough has the same dominant strategy. Grind up gfs while keeping your chars levels low, create and junction powerful magic, get Lionheart, cast aura, win. Wow, so simple for all the dicking around getting to that point will cost you.
Those are my top 5 issues, but I could seriously write a book about how much Final Fantasy 8 sucked. Don't get me wrong, I can tolerate it. I occasionally enjoy playing it, but I don't delude myself that its in anyway a great game. Maybe it's special to you, and that's just dandy, but to say its the bestest one EVAR is just ignorant.