Talking to people who have come to the UK from Europe and America I've been told many times that we are lucky enough to have some of the best television in the world. I'm very happy to pay my license fee and contribute towards the BBC. We do have some very excellent documentarians Adam Curtis being one of my personal favourites.
It may be that I'm something of a spoilt brat complaining about my toys being taken away, I grew up with excellent weekly factual documentary strands like Panorama and Arena, and Tomorrows World which was not a documentary but a fondly remembered weekly science show, now cancelled and not replaced. During the last decade the overall frequency and quality of these shows has declined very sharply.
Documentaries used to trust their audiences, but now quality is apparently judged by viewing figures alone the public service content of any channel has to fight against entertainment programming and they've slipped too far towards entertaining the audience viscerally rather than mentally.
Documentaries are now filled with fluff and sensationalised content and do not treat the audience with the respect they once did. A brief example being a 2010 Panorama doc about CERN and the LHC which felt like it consisted solely of asking as many scientists as possible 'Is the LHC going to cause the Earth to be eaten by a black hole'; For an hour.
[edit] I tend to think this is happening mainly in sci/tech programming, the humanities are still well covered.
Also I realise this might sound like I'm complaining about factual programming as entertainment. I realise that it should entertain and be accesible to an audience new to the material. I'd just like it if they remembered to slip in some facts now and again.