Our "open" class is less restrictive than WFTF - we allows thigh/leg straps and 20 ft lbs of energy. Any clothing is allowed too. Even with this many open shooters opt to not use shooting jackets. They have downsides as well, especially in the hot summer and fall months in many states. They are heavy, can make you very hot and in theory could cause just as much discomfort as support.
I think that you have to draw the line somewhere of course - probably don't want people setting up a bipod with a remote trigger at the lane. But I'm not sure it's the jackets that turn people off or even expensive gear. I think it's just perception. We've had several national champs in our hunter division using essentially $350 used Crosman rifles. I really don't think that expensive rifles or gear make the shooter better. It makes things incrementally better or easier and perhaps even adds a mental advantage if you are fully confident in your gear. But I've fallen into this trap.... I shoot very infrequently. As primarily a forum jockey I start thinking that time spent obsessing over rules and equipment and clothes will make me better. "If I just had item X I could beat so and so". It's human nature I suppose. Time spent shooting what you have and practice, practice, practice pays far more dividends. My guess is if you took away coats, butt hooks and March's from the top shooters they'd still be the top shooters.
Just my 2 cents.