Resolution matters. When developing software, I tend to have running an IDE, a Web browser or two, and several console windows. I want to be able to see these at a glance, and that requires pixels; lots of them.
In 2008, Lenovo released the ThinkPad X200s. With its compact screen boasting 1440x900 pixels at 12.1", I decided to pick one up to use as my daily driver.
It is now nearly three years later, and I have yet to buy a newer computer. Lenovo released a successor, the X201, and is poised to release another successor, the X220. Both of these sport faster processors, bigger storage, and other impressive specs, but they are both missing improved displays. In fact, both successors sport lower-resolution displays than the X200s. This just won't do.
Since screen sizes vary, directly comparing absolute resolution can be misleading. What is important is pixel density, so that a larger display will have correspondingly larger resolution. This can be roughly calculated by counting the pixels along the screen diagonal, and dividing by the screen diagonal size. For the X200s, this comes to about 140 pixels per inch.