Because the other two long-term consequences that players really care about IME - those being 1) permanent level drain and 2) item meltdowns due to AoE damage - are no longer available by RAW.
Oh these things can be kitbashed in alright, and easily; but only over howls of protest from the player base and at great risk of coming across as a rat-bastard DM.
Far easier for all had these other long-term bad consequences been left in as default RAW with options presented to take them out if desired for one's own table. That way, the DM who runs it RAW is just running the game, while the DM who exercises the removal option(s) comes across as a nice guy - or a softie, one or the other.