Ah, so it's 50+ pages, not 1000+ posts as I thought. Getting my BBs mixed up. (It used to be 1000+ posts on Enworld but there seems to be no limit now).
Let us not forget that he wrote the sitcom Coupling, and I think a lot of that style sometimes leaks over into his Who.
Most notable during Tom Baker's second season, where pretty much every story was inspired by a classic horror trope. But the first and third Baker seasons were also largely darker in tone than what had gone before. Which could be why they are some of the best. In my mind, anything that upset Mary Whitehouse had something going for it.
The First Doctor serial "Edge of Destruction" is an odd two-parter between "The Daleks" and "Marco Polo", so the third story ever, where a fault in the TARDIS sends it heading back to the start of time, and basically involves The Doctor, Ian, Susan and Barbara getting angry with each other under the pressure (also at this stage the Doctor has effectively kidnapped the two teachers and it was his fault they got stranded on Skaro). I'd like to see a retread of that.
And don't forget that all the First Doctor historicals (and the first few Second Doctor historical stories too) don't feature alien monsters, although as you say a "given level of monster" you might include Nero or Robespierre as a "monster". Quite often, though, the human adversaries are quite nuanced (see esp. The Aztecs or The Crusades).