Why fight optional bosses?

[Syrin]

This may have been addressed already, but the Steam search option hasn't worked for two days for me. On to the point, you get no reward at all for fighting anything, so why fight a boss? What am I missing?

[1100011]

Topoda unlocks parts of the map,
the Consortium gives you a win button with sufficient umami, and a shortcut.
Inkterton first fight gives you a chance to learn his moves for the real fight (a mechanic that I absolutely love, it's a bit like an in-game dojo. If only we got that for Waterfowl... in stead someone had to make a dojo mod).

Edit oops spoiler markers.

[Syrin]

Ah, okay, thanks

[Doctor Tex]

Those three mentioned before give more tangible rewards. The rest are just fun challenges that give you a crabton of crystals. Useful if you're upgrading yourself or your adaptations.