I understand the reasons why they feel the need to mix things up a bit. To try and keep things feeling fresh. But to be honest, if your priority is to save money because the BBC can't give you as much as they used to, then the last thing you should be doing is green-lighting new Cyberman costumes or new TARDIS sets. It's an incompetent management of resources that could be better used elsewhere, IMO.
I feel that the amount of money saved would, at best, give you one more episode. They could also save money by doing a bunch of bottle episodes, but that would probably lead to a decline in quality. I don't see that being ideal either. I think the goal is to have fewer episodes at a high standard. I don't think that's unreasonable. More is not always better.