I disagree that Andorians would be rare. I would actually expect a fairly sizeable output of progeny. In our campaign, they're almost as common as humans.
Why wouldn't we see them often (other than make-up & budget constraints?) Early Starfleet might have had trouble with their food requirements; figure they have pretty odd (by iron-based standards) requirements & it was too much hastle to integrate them early on...that plus their family social structure needs.
By the movie period we start seeing them more often in the background. Figure by this point they were perfecting food processors to be compatible for Andorians and other races.
I pretty much use S JOhn's Andorians; I like 'em. However, I like a few of the other ideas for their physiology that I've seen here.
My two ducats.
"War is an ugly thing but not the ugliest of things; the decayed and degraded state of moral and patriotic feelings which thinks that nothing is worth war is much worse. A man who has nothing for which he is willing to fight, nothing which is more important than his own personal safety, is a miserable creature and has no chance of being free unless made and kept so by the exertions of better men than himself."
John Stuart Mill