Guildhests reward the whole party for their efforts... so why not leves? You can party up in them, so why doesn't the party get any rewards for the same efforts? I found them to be a fun change of pace with friends, but it'd be nice if a few things were changed to accommodate 1-4 people joining.

Based on how many are present, the difficulty, enemies spawned, etc. can be raised or lowered. Just make 4 versions of the same leve or something. Have the one person spending an Allowance get rewarded more, if have others chip in their own to raise both risk and reward. Finally, at turn in, give experience/gil rewards to everyone that participated, not just the one that initiated the instance.