It's not like I'm saying I hate classic fighters, or that there aren't any I still enjoy today. I've got plenty of hours on FightCade just dicking around in various random kusoge. I'm traveling to Combo Breaker in two weeks, and I signed up for six different brackets, two of which are retro titles (Waku Waku 7 and Twinkle Star Sprites) (you could also count Mystery Bracket, but the point of Mystery is to play trash that doesn't hold up).
But the games that have stood the test of time are few and far between. They're the exception, not the rule. If you think your game is too good for patches because it worked for Vampire Savior, you're a lot more likely to end up like SVC Chaos.
From a developer's perspective, they have to adapt to a changing market. All your competitors are iterating and improving their games, you need to keep up.
And hell, some of the most popular classics are patches in a sense. People play Super Turbo and Third Strike, but no one's playing World Warrior or New Generation. At least now players don't have to buy those kinds of 'patches' for full price.