Well, I actually believe the main reason why the Radio 2 and 5 Live main boards were axed is because they were getting attention from the press - and it wasn't good attention, either! Plenty of posters were up-in-arms with goings on at Radio 2 and 5 Live.
For example, the appointment of Chris Evans on Drivetime accumulated well over 1,500 complaints on a single topic! Ironically, though, the actual topic was posted on there by a Radio 2 Messageboard Host on behalf of Lesley Douglas! Then of course, there was the appointment of Russell Brand to Saturday nights and Sarah Kennedy accusing the buyers of her home of being "thieves". None of this was good publicity for Radio 2 and was getting attention from the press.
The same applies to the old 5 Live messageboard - when the presenters protested against the amount of negativity they were getting on the messageboard! A clear sign that Auntie Beeb doesn't like criticisms. Oh well.