A few thoughts...
1. I don't think BT's baulking at the cost - look at the billions going into 21CN.
2. I'm actually happy to see them get 21CN out of the way first, because it will give the country a far better backbone off which some of this natty new stuff can hang. Moving the core of the network to IP will make it easier, cheaper & quicker to provision new services of all kinds in the future - though of course this does nothing to address the copper/aluminium/soggy string presently linking most of our homes to the world. I don't believe any other major global telco has yet done what BT is currently doing to the core of its network (though I stand to be corrected if I'm wrong), so shall we stop all the pointless hand-wringing & trying to convince ourselves that we are world+dog's poor relation when it comes to telecomms?
3. Maybe we look a bit late coming into this ultra-high-speed access game, and we could argue about chickens & eggs ad-infinitum, but the apps for that kind of bandwidth to the home are really only just getting started.
4. Show me the evidence that not having multi-gigabit broadband to the home is damaging the economy /now/, or in the next 5 years and I'll worry. Until then, I'll assume that neither BT nor the government is stupid, and that in time (if only just in time!), these technologies will come.