Cycling, despite all the drug problems, is kind of in a similar place right now. You can go buy a road bike right now, that weighs just over 10 pounds. But the pros are restricted to using bikes that weigh at least 15 pounds. Some pros have even been known to add lead weight to their bike in order to not run afoul of the minimum weight limit. Note: This is completely within the rules.
I think that at the amateur level, there should definitely be rules about what kind of equipment you can use. Otherwise, many people who might end up being great at the professional level will never get there, as they were discouraged by the fact that they are continually losing to those with more money.
On the other hand, the professionals, with rich sponsors, it makes little reason to try and limit specific technologies. Obviously you want to disallow anything that would make the athletes unsafe. You probably also want to keep the general idea of the sport the same. Such as no recumbent bicycles in bike races meant for upright bikes. But limiting things like the fabric on curling brooms or the shape and material of your swimsuit seems like it's pushing things a little bit too far.