I feel that some of the biggest factors driving people away from vintage are WotC's departure from its old design philosophy. Recent cards tend to have banal art, titles and flavor texts compared to many of the older cards. Too many of the recent cards refer to some planeswalker. Too many titles are Jace's this, Liliana's that. Too many flavor texts are just: 'I'm planeswalker x, and I feel this way!' (e.g. Act on Impulse) Too many artworks are bad computer generated art depicting a planeswalker with smoke and sparks coming out of their orifices. How many Jace cards should there be? How many cards should refer to how 'badass' Liliana is? How many more planeswalkers are going to be bad parodies of comic book superheroes and villains? Corny pop culture stereotypes are replacing the cryptic intrigue and mystique of older cards. One of the aspects that I like about Magic's premise is imagining that my cards are my spells, and that I'm the one casting them. Ganging up on my opponent with imitation superhero buddies isn't appealing.
More importantly, many of the recent cards have boring mechanics that reduce player interaction. Look at Cavern of Souls: there are very few strategies that can interact with what is being 'summoned'. It's a dead end in terms of player interaction. If you use it to summon Thalia, Gaddock Teeg, Ethersworn Canonist, etc. turn 1, continue to pump out your taxing creatures and artifacts turn 2 and 3, you've locked your opponent out of the game.
Planeswalkers are another example: planeswalker abilities cannot be easily interacted with in a nuanced way when they are in play. You either attack them with your creatures, cast the select few removal/counter-trigger spells that apply to planeswalkers, or shut them down completely with Pithing Needle and the like. So many of the awesome old artifacts, counterspells, and removals need to be sidelined if you want to beat them consistently.
It's completely understandable that many people don't want to pit their cherished Magic cards against what are effectively Pokemon and Yugioh cards (not to disparage them). Playing 93/94 is not the most inclusive way to do this, but it's one way to get rid of bad design decisions that have been tacking onto Magic over the years. I personally would love to see a format that limits itself to all pre-modern sets.