Thanks for the response, but could you clarify with some of your reasoning?

I've looked at a few frames that I own from 2007, and even those, with their ugly welds, don't have these weld craters anywhere.

I hate to be so nitpicky, but I do plan on sticking with this frame for the next 4+ years, and wouldn't want it to fail prematurely. I did research on welding craters, and found this, along with other welding forums that seem to come to the consensus: "Fill the weld crater at the end of a weld. Craters are the leading reason aluminum welds crack".

Seeing as how the bike will be used very regularly, it seems very likely that the vibrations and stress will cause the frame to fracture/fail at those points.