Because the LCARS GUI is only for simple recurring tasks, so it's easy to find an optimal interface.

Complex tasks are done vibe coding style, like La Forge vibe video editing a recording to find an alien: https://www.youtube.com/watch?v=4Faiu360W7Q

I do wonder if conversational interfaces will put an end to our GUI churn eventually...

Conversational interfaces are slow and will still be slow even if AI latency will be zero.

It might be nice way for making complex, one off tasks by personnel unfamiliar with all the features of the system, but for fast day to day stuff, button per function will always be a king.