Can anyone explain why the idea is raised so often when wakelocks are discussed?

Because power management is critical to using your computer...

If you have a nasty app that won't sleep, your battery is flat in 2 hours when you thought it was going to last all day in idle (do some work on the morning commute, close/suspend your laptop for the day, open it at the start of the commute home only to find it's dead ...).

But the other way round (as I've been bitten, by linpus/Acer One) is that you do a network mv, then the laptop suspends and shuts down the network. Hang on a sec - I've just left my computer to get on with some work, and it shuts down! What's worse, because it was an mv, the shutdown unfortunately broke it with the result that a load of files disappeared in transit :-( !!!

Cheers,
Wol