SLR is superfluous in a digital camera, but old habits die hard, I guess. You simply don't need an optical viewfinder in a digital camera, and thus don't need a complicated SLR mechanism.
I disagree, the display on the cameras is no match for the final product and no match for seeing the real thing.
As far as the 'complicated SLR mechanism' I see lots of old SLRs working fine, I have already thrown out more then a few digitals because of failure.
JMO, Bob
Bob Badger Construction & Maintenance Electrician Massachusetts