Funnily enough, originally the game was planned to be endless, maybe just keeping track of how far you got. But at the end we thought fighting big, boss-like enemy was a more satisfying ending.
Even after saying that, I do think there's so merit in the idea of having some sort of endless mode, and maybe even a leaderboard as you guys were discussing on the thread. But having a satisfying version of something like that will involve bespoke rules and progression compare with the current game, so I guess the only thing I can say right now is that we're more focused on the "story" mode of the game. Hopefully you can see where I'm coming from with this answer :)