Yes.
And definitely something like WoW.
I was talking to a friend who actually hated LoL because he just didn't like the MOBA playstyle.
However, he did love the characters, and would play the game if it were a completely different style.
Which I thought the same thing a while ago:
LoL has become so competitive that we treat these amazing Characters into tools, we don't see the magic and fun of these characters and we instead use them as hammers and/or swords rather than playing with them like fun and addictive toys.
Which is why I would definitely agree that having an MMORPG with League of Legends' characters would be a super fun way to explore and experience Runeterra more efficiently.
That or Sandbox Mode.