I'd hardly say that the BBC is getting a free ride - they pay for their internet connectivity, after all, and it's a pretty hefty sum, getting that data to a place where it interconnects with the other ISP networks.
Of course, after that, yes, it takes up space on the network - just like traffic from every other service.
I don't see a really good argument for charging companies like the BBC or YouTube, but of course it's an attractive proposition to the ISPs, because they get someone to blame, and they can try and dip their fingers in the licence fee pot to prop up their failing business plans.
The real problem, of course, is that for years ISPs have been competing in a race to the bottom, claiming to offer the fastest, most unlimited services, for the lowest price possible, and shedding every bit of cost that they can, in the name of greater shareholder value.
As a result, they have creaking networks that can't serve the needs of some of their users. They should be investing money in those networks, rather than lining the pockets of shareholders for short term benefit.
And yes, perhaps some users will have to pay a premium for a less restricted service. If they complain, the main cause of that is surely not the BBC or anyone else providing IPTV services - it's the fault of the ISPs who pretended they were selling an unlimited resource, with misleading advertising ad obscure 'fair use' limits, when they really weren't doing anything of the sort.
Even without IPTV, the broadband that many people have been sold doesn't match up to the description. Attempting to put the blame at the door of broadcasters is shifting the blame; IPTV is a convenient think to point at, but we'd have reached the same point sooner or later, thanks to the unwillingness of so many companies to take a long term view.