I lived on a 1280x960 19" CRT for years, and when I upgraded, I knew that given what I do (plenty of work in Photoshop et. al., and almost no gaming), I needed to expand in both directions. Widescreen is cool and all, but to match the vertical resolution of my Samsung 213T, I would have needed a 1920x1200 widescreen, and at that time the Dell 2405fp was almost twice the cost of the Samsung as I recall - thus to say, simply not an option. The 2005fp, while a nice monitor, would just be too cramped for me.
And that is not considering that on a Mac (which my PB15 with DVI output obviously is) the dock is usually on the bottom (I've never been able to get used to having it on a side of the screen), and unless you make it hidden, it eats away further at vertical screen real estate - something that is noticeably lacking IMHO on less-than-23" widescreen LCDs.
This is all my humble opinion, but some people are a bit short sighted in thinking that everyone needs to buy a widescreen LCD, no matter the size, because everyone watches enough movies and plays enough games to make it worthwhile.