Cause nothing's 'stretched out'
I'm surprised Windows even handles them properly at higher vertical resolution than their native. A 22" is generally 1680x1050 (vs 1600x1200), and a 19" 1440x900 vs(1280x1024).
Myself, I run a dual setup with a 22" wide and a 19" 5:4. The 19" is pretty much exclusively for IRC/IM and ObjectDock, while the 22" is where the real stuff happens. Works out nicely since they're nearly identical in physical height and vertical resolution.