I don't necessarily agree with you here, although I see your point. The builds seems limited initially, but that's until you realize how many different ways there are to actually play the game.
Arcane and Bloodtinge definitely cater to more advanced players, but they make for a completely different experience. Side arms are not useless, especially in the late game if you're playing a Skill character. When you're playing a character based around the Skill stat, the side arm becomes integral to counters and visceral attacks, allows you to keep distance between you and the enemy, using weapons like the Gun Spear, keeping a secondary weapon on hand for closer and faster battles.
Playing the game with Arcane weapons is basically the new Magic build. Using your own health to make weapons is incredibly dangerous, but because you can build your character around this ability, it's also intensely rewarding. Mix this with the Bloodtinge stat and weapons that benefit from both and you have a few options for a much different play experience.
A purely STR build means you can ignore your sidearm completely and focus on 2 handed builds, while mixing both Strength and Skill means you can find some pretty nifty uses for those massive side arms for killer damage, like the canon.
Lastly, the health recovery mechanic never becomes obsolete. There are some enemies where the risk outweighs the reward, but learning when to stun and when to attack makes this dance remain exciting throughout the game. There are some bosses, especially later in the game, that deal massive amounts of damage. Balancing your health potions with health recovery is important. Learning when to attack and when to cower and heal yourself instead is an invaluable skill.
The game isn't as diverse as Dark Souls in this regard, as you mentioned, but I never really played DS in such a way that those silly builds were all that important to me. Bloodborne is more streamlined, but it's individual systems and mechanics feel much more fleshed out because of it.