[MegaBlues]

I think that the first step to making leveling more interactive is to smooth out the exp curve at higher levels, then make different levels of challenge for different styles of play. Easier, simpler dungeons for newer/lone players who don't have a perfect build or equipment setup, then more intensive dungeons for groups and those who have a more polished build. I would also review monsters, because due to mixed dungeons, avoiding certain monster types is impossible, and those monsters can be fatal to certain builds, if not all of them (firewings, corrupters).

The tower is used because it's a predictable fight with similar enemy types and doesn't require navigating a dungeon which may hurt your eyes or requires playing a spot-the-difference game to proceed. There also isn't a need to search out a dungeon in your level range, and healing is readily available.

(Also I apologize if my tone was a bit confrontational, I can imagine balancing enjoyment for newer and older players is difficult)