I think flourishing can play it's part in magic. But to follow on from Goldfish's point, you certainly need to ask yourself why you're doing it...are you just showing off for showing off's sake? (Points to the door...)
I have a really simple trick I do called "invisible cards" that I got off a Gerry Griffin DVD. Supposedly using a fancy false cut will magically bring their card to a position named by them (a number from the top of the deck), but when it doesn't work you try it with an "ID" (not the prop, a deck that's actually invisible) and mimmick an even fancier cut with these "invisible cards" saying you must not have got the cut right. Then you count down the same number of cards in the "ID" and show them their invisible card. They of course are not impressed, but then you name it. Then you can go back to the real deck and try again after "regaining your confidence" and doing another cut the card is at the numbered position. Sorry if that was condensed and unclear, I might make a video of this trick soon (competition entry comes first though) as it's one of my favourite impromtu routines.
I like this trick and decided to change the presentation a bit to involve some funky false cuts (normally Trinary or my version of the Pendulum Cut) to add a bit of eye candy to the trick and make them think I really do have that much control over the cards (even though I get it wrong first time).
I think Sankey makes a good argument for using Flourishes in magic. His argument is that (especially in restaurant/walk-around magic) you don't have much time to impress your audience, you get 10-15 minutes at the most with a close-up set usually and you need to be able obtain some credibility right from the start so doing eye-catching things such as Card Springs and Butterfly Cuts instantly tell your audience that this isn't "Uncle John" at the wedding reception, you're someone who might actually be good at this magic stuff (apologies to anyone who's uncle John is actually a competent magician).
EckoZero wrote:
I make shuffles etc very sloppy, and try to only use moves used by card players.
Although that's probably because I have digested RRTCM and Hugard makes the valid point that if you seem to be sloppy and somewhat inexperienced, it's a much more magical experience. And if you just show off all the time people will discount your tricks as knowing how to handle cards...
From experience, I personally find that showing a good card handling skill with a funky cuts and springs and stuff does prove your point but I don't find this a bad thing. Unless you perform for children your audience will not believe what you did was ACTUAL magic, they know it's done with gimmicks and sleight of hand, but they still don't understand how these work and enjoy being confused by these techniques and props.
I personally find that demonstrating a card ability above the average joey in your local pub will often suspend their pestering to know how it was done and leave them just in awe at what you just did because they think even if they found out that they wouldn't be able to do it (without alot of practice).