The 95% constant segwit signaling required for activation must have been set that high for a reason. I would think it is more for a transitional security reason than for winning a popular vote contest.
Good guess.
It's not security, but stability, that informed the choice of a 95% activation threshold. Specifically, stable coherency of the Bitcoin network as a whole.
If the threshold were set lower, there is a risk that those miners running software that cannot handle the fork would reject blocks featuring whatever new feature the fork enables. Regular users also running pre-fork full-nodes could reject the same block too, and an actual ongoing blockchain fork could occur, totally unplanned and unwanted. The idea with soft forks is to make sure older nodes can continue to use the old feature set on the same chain as the new feature set.
Call it security or stability if you wish. People want both.
How does User Activated Soft Forks help with this? Miners don't signal for segwit, so impatient users demand soft fork to force miners. Is the network stable or secure now?