We may not really need it, but the equipment companies sure do. It's all about the $$$. Take away reactive coverstocks and you're taking away the vast majority of their products for sale. Can't really differentiate a whole lot with urethane and that would cause a problem with competition between the likes of Storm, Ebonite, Brunswick, etc. Then there's the trickle-down effect to the other stuff like certain cleaners, polishers, etc. that would be rendered obsolete.
The visual aspect of it also has to be considered. Urethane balls (and especially polyester) aren't going to look as pretty hooking down the lane and going through the pins as reactive balls regardless of how short/light the oil patterns are. Those who put an extreme amount of revs on the ball are the obvious exception, but they also don't represent anywhere near the majority of bowlers. If the game is going to grow you have to be able to sell it to those outside of it, and I really don't think going down this route would do that. Looks are as important as anything these days.