Welcome back.
As for sacrificial lenses, in photography where neutral filters are cheap and available and designed to fit in the threaded lens housing, you're basically buying a thing that is not designed as a sacrificial item to be sacrificial because it's cheap. In airsoft there's loads of killflash fittings that slide into or over the lens tube so it makes sense to pursue that avenue for sacrificial lens protection as opposed to making a threaded fitting which would be more expensive. In terms of the rail mounted ones, I agree that they are ugly AF but again, the rail space available makes it easy to fit and forget.