Scott,
I think you missed Westcoast's last point, that with the automatics in and the crew misses the restriction, it's a problem of systems management and not a problem with automation. The time for head down programing the box is way back prior to top of descent, 99% of a requests from ATC can be accomodated through the crew making a selection on the FCU which should only take moments to exicute. Sure, on the 1 in 10,000 occasion that the aircraft isn't doing what it's suppose to (there are the very occasional software problems) then sure the automatics come out and the deviation corrected. We all practice raw data descents and approaches when the conditions are appropriate. as you say use it or lose it. However descending at 300kts, raw data, into a busy terminal area greatly increases the chances of missed clearances. It's all about increasing the safety margins. Any crew having problems getting the FMS to do what they want it to do, should dust off their manuals........