Whole cans are easy to recycle, but doing so requires melting the metal back into stock and noxious chemicals to clean the metal.

That is all very expensive and environmentally unfriendly compared to potential for reuse of strong bottles.

Unless you force a redesign so that cans are reusable. (No more tab - instead a bottle cap, standard shape, no crushing, heavier, thicker, more expensive.)

I expect that soft drinks could easily be sold in a mini-keg form factor.

There exists aluminum bottles - Coke at one time sold their soda in them (I think it was some kind of commemorative edition or something like that).

That would have the same benefit as bottles: The ability to drink only part of the contents (like people do with water). The downside is that you can't see what is inside (an important factor for many people when they purchase - especially water).