You may well be correct that a new crank isn't needed. I'm rather new to all of this. Some of the teeth appear rather scraped up to the point where they seem shorter than they should be and are a bit deformed. These teeth are located together in a rather small area of the chainrings and the largest ring is most effected. Perhaps an accident? It appears that the chainrings are riveted on, so changing them looks to not be an option.

Anyway, part of my goal is to generally upgrade the bike. From this perspective, it seems to me that the crankset could definitely use replacement.

The Sugino does look appealing.