I'm glad to hear that other Aikidoka practice hard enough to get bruised.
I find that I I still get bruised while working with new students because they have a tendency to grab your skin instead of using good ki grip or leading in their techniques.
Being hurt is different than being injured, though. Juswt because you've got a few bumps, bruises, and brush burns doesn't mean you are injured. Injuries usually require healing time and can keep you from practicing for extended periods of time. Those should be minimized as much as possible, but are unavoidable in a contact martial art like Aikido.