Fair enough, I'd hate to see the day when someone who really has no way of getting a plan in is held or refused clearance for no good reason. However, I think it's a bit of an insult to the air traffickers to say that asking if you have a plan in the system is inane.
Like I said, the change came in with the systems upgrade they got some years ago, and while they can of course still handle on the spot requests, it's not expected to be the norm. Anyone who can put a plan in should, because it makes their and our lives easier in the end.
Tech-savviness isn't really that much of an issue - most people would have the internet available somewhere prior to flight and could whack a plan in either via the airservices NAIPS login or a phone app which is really no more difficult than phone banking.
The AIP (itself very easily downloadable off the airservices site if you don't have a hard copy lying around) sets out exactly what all the bits in the plan sections mean, so anyone who spends a little bit of time going through it and having a practice at submitting a plan won't have too many dramas if they were cluey enough to get a licence in the first place.
I would like to stress I don't mean this as a criticism of anyone, and you probably know all this anyway Aussie Bob, but Dick puts it out there as bastard air traffic controllers denying good old pilots a clearance, when really I feel it's a limitation of the system they have to work with, and not too hard for us to learn to plan if we're going into CTA (or near it if that's relevant for transit lanes etc).