That's partly because you NEEDED to hit the level cap to do the new endgame, because (like kings fall) the content was a higher level than the players, so you HAD to hit the cap in order to be able to play it. The other factor was that you could hit 34 in one day because an exotic from Xûr, an armor piece, and 2 etheric lights from PoE got you to 34 instantly, no need to level anything, just equip and go.