https://en.wikipedia.org/wiki/Recumbent_bicycle

I doubt that any pro-cyclist wants the speed advantages of one if it means that cornering is more difficult, veering into dangerous.

I am also pretty confident that the 'manoeuvrability' disadvantage is completely irrelevant for any individual track event. And do you think that it would be an important factor for time trials?

[edit] And yes, for time trials recumbents would be nice, but already time-trial bikes are pretty different and unsafe, I don't think the UCI would allow even more risk.

Maneuverability is important for time trials. Most courses have several tight turns and crashes are common.

Things like better shifters, lighter frames (within reason) more aero parts (within reason) are still allowed.

The UCI's 6.8kg weight limit is much higher than what is achievable with modern materials. So much so that there are frame builders who can build you an "illegal" bike made out of _steel_: https://www.rodbikes.com/catalog/outlaw/outlaw-main.html

With a minimum limit, no one feels the need to make their bikes less than perfectly strong. And when every OEM is making frames at perfect strength under the limit, they drop it.

https://en.wikipedia.org/wiki/LZR_Racer#Marketing_and_result...

https://en.wikipedia.org/wiki/Arena_X-Glide#Controversy

I’d also argue there is a difference between rules about equipment and rules about technique. Technique rules may have to be adjusted more often because if an athletes does something unusual that is within the current rule set but may be seen as advantageous, you have to make a decision.

With equipment you can just say no. Those Nike running shoes are banned, full body swim suits are banned. The javelin is just another ban. With equipment, it also effects athletes uniformly, everyone must change to the new equipment. So no one is unfairly penalised.

Why do the records need to fall?

part of the competition part would be breaking records.