To be honest I think they need to be a little careful with what exactly they dumb down and how much they do it. By dumbing down I do of course mean such things as hiding the Library folder and Macintosh HD by default, among other minor things in Lion. I think Snow Leopard had a nice middle ground, it still had the simplicity without making things difficult for those of us who actually like to use our computers
One of Microsoft's biggest mistakes with Windows was the dumbing down of the UI, Windows XP for example had that new default view for explorer which dumbed down almost everything, which actually had the effect of making things very difficult indeed for almost anyone who wanted to use the computer.. even finding things in Control Panel became a cumbersome mess. I just hope Apple doesnt make the same mistake with their UI.