Well I truly don’t. Adding a development tree to a shooter is not an artificial way of creating depth. Sure it could be handled poorly and create perverse incentives and everything but that’s not an objection inherent to a shooter with rpg-like qualities.
Character development is the base of RPG. RPG’s are usually purely cerebral games, even MMO’s have marginalised the cognitive aspect. This means that the entire genre is no more than a really elaborate Rock Paper Scissors game. RTS games and shooters have an enormous advantage here, regardless how strong the strategic side of the game is, there’s always the cognitive aspect that gets you by. These two sides work synergistic. A good aimer can out-aim a great tactician and a great tactician can out-think a good aimer. This creates an incredibly volatile mixture where players constantly having to asses which approach is the most appropriate.
ETQW is a game where it sometimes pays to reflect on the battle and adjust your thinking yet there are situations where it’s equally rewarding to toss away all stratagems and just brute-force your way through (often completely jeopardising everyone else’s mind-game as well). And most importantly, ETQW is a game where walking that balance is the most rewarding of all. Like a jazz musician working with a few key-notes and then improvising on the baseline whatever feels best and whatever produces the best sound.
I think that defining feature of ETQW can be enhanced by creating an even bigger polarity between the cerebral and the cognitive sides of the game. The permanent layer provides a map for development and allows the player to develop faster during the game enabling enough room to improvise on the side. Making permanent choices opens the way for making short-therm amendments during the game. And then, on top of that, kill streaks (similar system but totally not the same magnitute of rewards like in COD) to add chaos into the mix to shake things up.