The races UCI controls are supposed to be more about the cyclist's abilities than the machine they ride. So for one thing, it's important to control what those machines are and prevent any one bike from having such a unique design that might influence the outcome of a race more so than the strategy and strength of the cyclist.
Bikes and equipment must also be what is available or what in the very near future will be available to any consumer.
Your post title shows a little ignorance IMO.