It wouldn't surprise me if there's groups that had a bad experience with the newer version of
WM/H and decided not to upgrade.
Plus this is a great way to complete the collection for those who value that.
Not being a
PP guy myself, do these books have value for painting guides, fluff, or similar that might differ from Mark II versions?
For D&D,t here's a lot of people that still play 3.0/3.5 as the change is pretty massive to go to 4 and some people don't like that style. Plus 3.0/3.5 had a ton of 3rd party support, including a lot of games that technically require the PHB, so it may be easier. I like 4.0, but 3.0/3.5 might be a better choice for certain games.