I'm on the side that if something is either a lot more magical, or impossible to do without gimmicks, using them is all fine.
For instance, a classic 'Two Card Transpo' in the spectator's hands without a gimmick is a lot more troubling and less magical as it doesn't allow you to perform the effect as open and magical. But an 'ACR' with a 'One Way Force Deck' is just being lazy and therefore a no-go (unless you use the force deck as a kicker, of course).
But.. apparently this topic is more about gaffed cards rather than gimmicks in general. Doesn't change my view on them, but yeah, there is quite a difference.