Excellent points; I haven't installed a ton of cameras yet, but so far I've powered up every one on my bench to at least verify it powers up and to configure network settings...
At work this drives me crazy, as most of my jobs are out of the country and getting parts/material is a pain... I can't say how many times I've wasted tons of troubleshooting time, assuming the item (usually some COTS media converter or similar) was tested prior to sending it to me, only to find out they never even took it out of the box...