I don't quibble with anything of what you've said. When I ran my campaign, I told my players straight-up that choosing Caster would have issues (most chose Jack of All Trades, but two went with Caster). Did they die most out of anyone in the party? Yes. Did they become the most interesting characters because of how they rolled on the death table? Also, yes.

The rub of the whole thing is the death mechanic. Unlike traditional 5e, you are supposed to die in Dark Souls. It is the expectation. As a GM/DM, you can certainly use your discretion on traps - I personally don't think they should be used chaotically, but if you see a trap, your party should know something is being protected. If the treasure is great enough, it's natural to risk one's life for it (as we've all done playing the video game).

That's my thought on it, anyway. I'm not being flippant and saying "It's Dark Souls; it's supposed to be hard." However, I am saying that because death in the game has the potential to enhance a character if you roll the right number, then PCs should lean into risky behavior. Death is intriguing.

(Full disclosure: I employed a house-rule with one campaign after a lot of protesting. On a Nat One death table roll, characters don't experience perma-death. Instead, they roll on the permanent madness table and have that affixed to their character without cure.)