I get the spirit of "method doesn't matter, it's the effect that counts!" and appreciate and agree with it to an extent, but, people, the method does matter. There are situations where some methods just aren't practical. There's some situations where you have a personal reason against a particular method - if your trick's method is sleeving, for example, you may be opposed to it if it's the middle of hot, hot summer and you're going for a casual look. Or if you're standing up for the entire performance and an effect calls for lapping. Are you going to bring in a table and chairs while outside just for that?
I know it's splitting hairs, but the method isn't entirely a throw away non-concern, and treating it as such is irksome.
As for the original question: not attempting to accuse anyone here, but some younger magicians stick to sleight of hand only and profess a strong dislike of gimmicks because they want to use sleight of hand, want to be purists, and they want to do that so they can feel awesome because of their ability. They're not worried about the effect, the audience, or the method - they're worried about bragging rights. Using gimmicks takes away from their ability to brag about how many moves they can do.
But, of course, there's also people who prefer against gimmicks for any other reason, and by no means is the above the majority rule. It's a strong, prevalent rule, but, depending on demographic, probably not the sole excuse.
I'm for either one. I don't like extremely tricky sleight-heavy stuff, preferring fewer, simpler moves, and if I'm operating some sort of apparatus, it needs to be practical, in terms of visibility, operation, and extraction. It's surprising to see how many people don't concern themselves with those three things when designing their gimmicks or the routines around them.