Yes, it was sold as an 'all you can eat' service, and yes, there were no such constraints previously, but pragmatically there's finite limits with satellite services, and equally, you're going to always get customers coming in and 'taking the piss' out of these services.
It's hard to not get a tad grumpy when your modest Citrix session at 300kbps is throttled because it's competing against 25Mbps streaming video (and you just know that plenty of those are the weird 'have the TV on in the background all day' people).