Keep in mind that dual monitors is completely essential in the business world, when you have to connect a projector or other large screen for presentatios, group conferencing and so on.
And people with laptops who connect it to a nice display when possible, their TV, etc.
Monitor issues are the single biggest source of aggrivation in my Ubuntu-related life today. :) Note that the problems are much worse with NVidia hardware, and their $*(#awful control panel. It's like playing Russian Monitor Roulette when you hit that 'apply' button. It might work, or it might completely mess up both displays, crash Lightdm, still have displays but no titlebars on windows and applications not being responsive, etc. The list is endless and it's a huge mess right now. It basically requires a reboot right now, IF you managed to get the xorg.conf file configured properly so the second monitor starts up on reboot.