Between the beer drinkers in the house, visitors and stuff given away I reckon we can get through five gallons in a couple of weeks or thereabouts and storage isn't a problem, so for me ten gallon or larger batches are reasonable. I'm quite happy to build up a "store" of a few gallons each of various different beers, too. Up until now wherever possible I've done two five gallon brews on the same day (sometimes I'll do four in two days), so "going large" just makes sense for me.
I agree with your general point though. Brewing a large volume might look good and sound appealing, but unless you have the space to do it and the kit for storing it, smaller batches probably make far more sense.
James