Being unfinished means you should cut it some slack and not compare it to the other endings. As an unfinished product of course it will have issues. The finished version would no doubt have been different, and addressed your problems.
Maybe and maybe not.
Most games don't tack on endings as afterthoughts. These things have to be storyboarded. They have to think these things through before actually doing them. And since the ending isn't missing anything and doesn't break the game, it's either a finished product or close to finished. They took the time to build those scenes and they took the time to build them fully, with unique scores, sprites, and backgrounds. My points should have been spotted long before the end was this finished. At any point in production tacking on Protoman's scene would have been a mistake. And at any point in production the ending would have been bland. So I feel it's entirely fair to call it such.
As for comparing it to other endings ... it's a Megaman game with a similar end to many other MM games. Comparison is unavoidable.
Edit: the most credit I'm willing to give these guys is that Protoman was probably meant to rescue Megaman. MM is directly hit by one of those boulders and could have been meant to have a KO sprite at that point. There's a track of Protoman's wistle beofre his full ending music plays furthering this theory. Unless there's somewhere else it goes, it likely would have been used for this hypothetical ending.
That said, that's not the ending we're looking at and I've been wrong in my theories before. I can't criticize an ending that exists solely in my head. But I can look at this and dislike it. If that dislike is the result of the end being unfinished, it seems fair in a game that's unfinished.