There not mandatory mate but adviseable. Without them, you'll just get whatever camber the Springs give you which could be way out due to the fact the car is lowered 20mm about a fixed point.
My tyres wore evenly throughtout before fitting the Springs so the camber and tracking must have been pretty good. However, since having this done, the handling has been transformed. The turn in is sharper, the road holding is much better, and I seem to get less tramlining. Feels better on the brakes too. I'm well impressed to say the least.
It cost me £315 to have the Springs fitted and get the camber adjuster bolts fitted followed by 4 wheel laser alignment. This doesn't include the cost of the Springs, as I already had them.
The down side is the ride is a little harsher (to be expected) and the springs are a little noisy but nothing to worry about. You can't hear it over the stereo. I suspect its will settle down once the springs have settled themselves.