Why only have one life on Temple bosses?

In 0.3 you learned from previous mistakes and made endgame bosses more accessible by having unlimited attempts on the entry level tier. And most importantly you made the leagues boss also have unlimited attempts.

Why make the decision to only have one attempt when fighting the Architect or Atziri? That doesn't make sense and it is just too frustrating for the time investment it takes to get to these fights.