Prestige systems really only work in games that have a deeply satisfying core gameplay loop.
Chiming in on this, but isn't that pretty much the entire point of games like KF2? What you
can argue on is whether or not it actually
has a satisfying core gameplay loop.
For the record, I would. Then again, I'm always up for another hour or two of challenging shooty bang fun-time.
As for a prestige system, the reset-based, lose-everything style of prestige only really works for arcade-y competitive multiplayer games, e.g. Call of Duty. If we were going to have a prestige system, it would have to be the infinite progression style, where you can't stop, won't stop, never stop leveling up, but never give anything up either. And I also cast a vote for gaining special cosmetics only obtained through veteran levels, a special weapon skin (I propose that these skins also not be "obvious skin" style skins that have, say, a bunch of chibi penguins painted all over them, but instead alternate muted color schemes, different kinds of metal plating and
maybe matching camouflage patterns) for every weapon on that perk (earned in order of tier) at 30, 35, 40 and 45 and then a couple of player cosmetics at level 50.
For example, for Gunslinger, they could get weapon skins in a dark, glossy crimson metal and matte black furniture theme and a classic cowboy hat and old west-styled sheriff star in various colors. Maybe Berserker could get nickle-plated weapons with rose gold detailing and a cape and hounskull helmet in various colors. TWI could definitely have some fun with that, and fun is good.
As for the complaint that some people would just grind that out: Who gives a crap? Plus, by the time this sort of thing got made there would be a map blacklist and all those fun-destroying, potential teammate-absorbing and terrible player-creating perk leveling maps would be destroyed.