"I'm able to afford a TV licence, I couldn't afford to pay much more. "
I think you can make rational arguments for subscription, and for funding it out of general taxation (given that take-up of BBC services is probably higher than many other things that are funded from general taxation). When I'm channelling Adam Smith and being all free market, I veer towards subscription, when I'm clutching my Guardian vouchers and berating people for voting Lib Dem in 2010 and thus keeping Labour out I favour general taxation.
What I can't see the argument for is a flat-rate, essentially compulsory, levy. It's a regressive tax, of the sort that anyone of the left should be very nervous about (because of its effect on the poor) and anyone of the right should be nervous about (for a whole stack of market distortion arguments I can't quite recall before my first cup of coffee). It's precisely the people who can pay, just, who are penalised: I can mutter about the iniquity, but 150 quid a year is neither here nor there and therefore it's a theoretical argument, but for all too many people it's a significant chunk of money for something which, for practical purposes, they can't live without. It's crazy that a TV license costs someone on benefits a week's income or more, while for others it's an hour's income. The TV License is a tax. It should be related to the ability to pay. Like (almost all) other taxes (let's not do Vehicle Excise Duty, eh?)
The free for the over-75s thing is precisely the sort of crap that made the last Labour administration (for which I voted, and would still vote) the intellectually incoherent shambles that it was (it was a typically ill-thought out policy from Brown's chancellorship). Few people are worse off at 76 than they were at 74, and not all people aged over 75 are poor; indeed, they're the prime "defined benefits" generation, and quite a lot of them (not all, perhaps not many, but more than a few) are well off. If the BBC is going to be state funded (on balance, I think it should be) then messing about with discounts and freebies for ill-defined groups who may or may not struggle to pay the levy is a waste of time and money: just give the BBC the money out of general taxation and have done with it.