Dell's monitors selection when ordering a computer has gone down drastically in quality. However, so has the price. Basically the last year and a half of advertising $399-$499 computers has forced Dell to skimp somewhere, and the monitor is the most obvious of their skimping.
For example, I just quickly went to Dell.com and randomly picked a home computer model. The CRT options that come up are (shipping is free for all these monitors):
17" E77c for $50,
17" M782 for $90,
19" M992 for $149, and
21" P1130 Trinitron for $630.
Since when can you build a quality 17" monitor for only $50? The dot pitch on that thing is 0.27 mm - something that would give nearly anyone a headache. It is clearly labeled as a "Value CRT" if you click on Dell's "Help Me Choose" button.
Dell used to have a full selection of mid quality monitors (their M series), and a full selection of quality monitors (their P series). Where the 17" and 19" P series have disappeared. Now if you want quality, you only get one option: the $630 21" monitor. Very few people buy a $630 monitor with a $499 computer. So the vast majority of what you see now are the midrange or value Dell monitors.