Well the question we should ask is why are these players going with the Classic Client. I can think of a few reasons:
1. The Enhanced Client is still in "Beta" - We are slowly working towards getting the client to a point where we can consider it officially released. We don't want to do this until we are sure its ready.
2. Their friend who got them to try it said the Classic Client is better - This is up to you guys. You might like the Classic Client better because you are used to it, but is it really the best client for a truly new player to use? Probably not.
3. Their machine can't handle the Enhanced Client - A reality we have to face as UO developers is that many people play our game because it runs so well on older computers and computers that are not meant for gaming. It actually give us an advantage over other online games. Since the Classic Client renders the entire game entirely in software (without the use of a graphics card) it runs great on these machines. However, the Enhanced Client makes extensive use of your graphics card and some computers simply won't be able to run it well.