Rust wouldn't be a better language if nightly were instantly made stable. Instead, we'd have a ton of half-baked features that we'd be supporting for eternity.

Rocket requiring nightly is unfortunate, and I wish it didn't, but aside from Rocket stable has been a good forcing function to get crate authors to not add nightly dependencies.

Anyway, from what I see, actix seems to get more buzz than Rocket these days, precisely because the former works on stable.