Funnily enough I was there with the kids on Monday, but didn't hear about this until the evening. It is looking run down now. Half the new 'interactive' stuff on the top floor was out of order, and the plane hall is really grubby.
There is a 'voluntary' suggested donation of £3 per visitor. I didn't see anyone else putting in, though. I think this whole outraged bit is a ploy to introduce entry fees. The first time I went I remember paying.
I just hope it's reasonable. I took the kids to Manchester airport viewing park to see Concorde. Right up until they demanded £30 (each!) to go into the building and get up close.