I think it's rather easy to fall into the trap of looking at this from people who have played Fromsoft games before, most of us to absolute death. What you say is true for us, but Bloodborne (or any Souls game for that matter) wrecks new players and from the perspective of trying to get new people to actually stick to the game, hiding an expected and obvious mechanic (leveling up) can cause people to quit or at least get massively frustrated, which I just don't find good design.
Honestly if all you cared about was the narrative trick and absolutely wanted to tie in the level up mechanic to it as well then I would've preferred you just gain zero echoes whatsoever beforehand to give a hint that something was up, and make vials more plentiful early on or something. The psychological aspect of just dying repeatedly, losing your currency and not having any idea what you're supposed to do with it sounds cool to us Souls veterans who know the formula inside-out and gives us the feeling of 'zomg what is going on!!!', but as an introduction to a new player, it just feels like progress being lost repeatedly without any way to compensate for it, which I cannot advocate.
EDIT: Also as an addendum, there are plenty of obtuse and stupid things like Cid mentions, Rhea from DS1 and whatnot that would never be obvious on a blind playthrough that locks you unnecessarily out of stuff. It's important to note that while I don't like these mechanics, they are 1) also very minor in the grand scheme of things and more importantly 2) come WAY later in the game and not right at the start, and none of them are as impactful as "how the hell do I level up?" Yes, the Insight gate is a hurdle that lasts very briefly relative to the rest of the game and can't permanently fuck you over, but it is also at the portion of the game where a new player's impression is most influential to whether they actually play the damn game or not. That's kinda important!
What I guess I am trying to say is that after enough dabbling with game modding/development and being in the industry I put an extremely high premium on making sure a player doesn't get discouraged at the introductory sections of games and think it is a worthwhile endeavor to compromise some narrative or artistic touches (you don't need to discard them, you just need to watch how much you tie it into gameplay) to make sure they stay onboard. Even for a relatively hardcore series like Souls series, even with their known reputation. There's plenty of room in the game to go hog wild with that.
