Some good tips on ultralight touring:
http://www2.arnes.si/~ikovse/weight.htm
I look at most folks camping on bikes and see too much stuff to keep up with. Real freedom is having almost nothing. Nothing to keep up with, few decisions to make, just the wind and the road, a nice cup of tea at an overlook, a quick dinner before the twilight, and then a dash into the woods for a nice rest under the stars. Repeat.
I've done light hiking and biking and can't agree. I have more freedom with a heavy bike. It all depends what you want to do. Shaving weight is always about a better ride but for me, bike touring isn't about riding, it's about traveling on a bike. I don't want to be tied to the road. On one trip, I stayed 5 days in a park with no resupply possibilities, in the fall (cold, wet, short daylight hours). I like to do some serious dayhiking too so I carry hiking shoes (riding with hiking shoes instead of SPD has been a debate with myself). Next trip I'll go backpacking for three days so I'll need a backpack. On one trip, I had 9 pounds of photo gear because... well, I like to photograph! I bought a lighter tripod just so I can bring an extra lens.
As gregw said, more weight on the bike doesn't hurt, it just makes you slower. I can live with that.