Current job ability limit (one job ability at time) is there because
some job abilities are very strong and if you combine two or more,
it might destroy the game balance, especially at the later
stages in the game. But having said that, I have one (hopefully great)
idea that I want to implement in the full version - still need some time
to vest this idea and haven't code it yet, but I think it will improve
the overall playability of this game. I'll share more information about this
once I've start coding.
About "finding exit soon", if you want, you can always save at Church
before you go to dungeon, exit without saving, then reload the saved record
to restart the floor. Or even better, use item to find the direction of the exit
and then try not to go that direction. That should allow you to stay in the
same floor for while if that is what you wanted

Yeah, having ability to float all the time would be nice accessory and as you said,
there are lot more accessories I can add in this game. I just have to make sure
adding strong accessory won't make game too easy - it's all about the balance
and I think this is most difficult part about making "fun" game.
(I have plan to add more equip item though - some that are rare and
maybe have special/specific effect etc)
I agree that leader board or some way to compare score would be good. It's just I want to
keep this game "without network" and adding online scoring mechanism of course need
some network. I know it's not like we need network all the time to support online scoring but
still we need to ask permission to use network and someone might have wrong idea
that this game need network connection.