Well… I’m all for the Altar in the off-season (and why not the Visions).
The altar provides a level gain of 3 or 4 levels (if I remember correctly). So it won’t kill the game.
The Visions are perfect for farming.
But… Do you really want to have an extra theme? Where’s the challenge? Enjoying your primordial gear and paragons? Run 150 in under 1 minute?