This does really make good sense. For most people, including me, Web access is slow, and pictures make it slower. I vastly prefer to access pictures and data from CD-ROM or hard disk. I use my catalogs frequently, but mine resides on my hard disk, so it is always there when I need it. Even more frequently than disk, I use printed versions.
Print is just the overall best way to present stamp data.
The color images on the disk are nice, but it is about as quick to pull down the correct binder from my collection and look at the actual stamp. The real benefit for a large image collection is for collectors who don't have many of the stamps. The best result so far is meeting and sometimes helping collectors and non-collectors. I suspect that the number of contacts would have been about the same with a much smaller site that didn't have on-line catalogs. I think that the site will become more useful as the general Web speed increases in the next few years.