CSS can be very tedious and difficult - it's probably not as bad on webapps (as apposed to websites) because you're not churning out a new project every few weeks. It's not appreciated and not particularly paid well so I'm not surprised that there is not many specialising in it. I find JavaScript development easier. A lot of the time in CSS you're searching for some "trick" to make the design work in all the different scenarios. The CSS toolkit is very poor especially when it comes to layout but that's changing with new CSS layout technologies but it will take time for them to be supported by all browsers.