The problem is - and I know London Andy will disagree with me! - that if everybody asks then the lounge gets overrun by children and becomes worse than a creche/playground and other (entitled) guests complain about the noise and nuisance levels.
Try this in the middle of school holidays at LGW with the MCO, TPA, BGI and ANU flights and you have somewhere in the region of 200 additional guests who shouldn't be allowed being let in every day.
Some of our flights at LGW have a hefty amount of children on board - one flight this week had 72 of them (and no it wasn't MCO!) many of them children of card holders.