It would be fantastic if players could hire heroes several levels higher than themselves in Crypt! I can understand not allowing this for Expedition or Temple, but it certainly makes sense for Crypt.
It feels strange when I delay adding XP to level up my best heroes for a bit just so that a few more guildies can continue to hire them. Further, we have gaps in our hire pool right now (bunch of players at 100, then some at 95, etc), so the players within the gaps don't have much to choose from.
Yes, @Little_Snow, the guilds consisting of players well below the server level cap have a pretty hard time keeping up, particularly when players have a wide range of power and level. My guild on server 4 currently ranges between 82 and 106 (with just a few at that level). No one is at the server cap yet.