I think that right now the P4 serves a niche market. What is this niche market you might ask? Either people with lots of money, ignorant people with lots of money, or people who use applications that can actually benefit from the P4.
If I ripped DVDs all day and had several thousand dollars to throw around, I might get one. However, for any one that has any sort of budget constraint, it doens't make any sense, at least right now. With the poor application support right now, there isn't any good reason for most people (or companies) to get the P4.
Perhaps later on down the road it would make sense, but not now.