The other side of this coin is the reason that high-end Receivers don't use SDR techniques in their front end is because the intermodulation characteristics of current A/D converters fall a long way short of conventional Superhet technology.
It will be a long time before an A/D converter chip can equal the performance of a high-level mixer. In fact it will probably never happen, as any advances will apply equally to both technologies.
But yes, I agree with you that few hams are building SDRs. This was my biggest disappointment with SDR. Five years ago I thought that SDRs would usher in a new area of home-brew, but it's evolved into yet another bunch of appliance operators who have little interest in writing the software. So sad, because it's such a fascinating field..
As far as I can tell the average user doesn't tinker with them much however.