Mr Awe wrote:
I find it completely credible that they could use the same set for that purpose. The new set is designed to look very similar to the original set. It should look similar in either production, which serves the purpose of both productions.
But the problem is that you're thinking only of design and not execution or context. They didn't have high-definition cameras or big-screen TVs 50 years ago, and they were working with a far, far tinier budget in an antiquated studio. The level of detail with which the sets were constructed at the time would look totally crappy by the standards of modern Doctor Who
productions. If they built the sets to be convincing as 1963 TV sets, they'd look awful if passed off as the real TARDIS interior. And if they built the sets to be convincing as the real thing in HD, then they'd look incongruously sophisticated as the sets used by a low-budget 1960s series.
Rebuilding the console room set to work in the anniversary episode would entail replicating or approximating the original design, yes, but in execution, in materials and details, it would have to be improved on so that it would be convincing by modern standards. In the same way that, say, "In a Mirror, Darkly" on Star Trek: Enterprise
rebuilt a TOS-style bridge and interior sets but put actual video monitors in the overhead screens rather than wrinkled astronomical paintings, and made the desk monitors smaller as well so they didn't look as old-fashioned. It had to look retro in design, yes, but still modern enough in detail to be believable in a present-day production.