I never really had a problem with the deaths, mostly because there are shortcuts everywhere. I can't think of 1 boss in the game that either has a checkpoint nearby or a shortcut. Usually you can safely run through the normal enemies on the way to the boss from the last shortcut.
The runs aren't that long either. For the first boss, just take the elevator up, go up the stairs, beat the first knight, and run like hell to the boss. Second boss has a doorway that leads to the room right before the final boss that has enemies that are way too slow to chase you. The giant ogres guarding the 3rd boss can be avoided entirely by going around them. The fourth boss, if you kill a special monster, only needs you to fight a singly weak crossbow enemy.
I have no problem with the respawns.