I've heard it said that at some point the Doctor Who TV series had a rule that they shouldn't have aliens which were just people in rubber suits. E.g. this claim about the Daleks:
The Daleks were created because the guy in charge of the BBC said "No rubber-suited aliens," so they made rubbish-bin aliens instead.
Now I've done a bit of searching online and haven't been able to find a good source for this claim.
From an interview with BBC producer Philip Hinchcliffe, who was responsible for Doctor Who in its Tom Baker years:
On the Daleks and whether he [Hinchcliffe] had a favorite villain:
The Daleks were foisted on me, I didn’t really want the Daleks. If you look at what I did that first season when they didn’t know who was going to take over and they didn’t know who the Doctor was going to be - this was in 1974. They thought, right, let’s go back to famous monsters and we’ll be safe, even if we’ve got Mr Pastry playing the Doctor - don’t you know who Mr Pastry was? He was a guy on a kids’ show but inappropriate really for the role – so they were playing it safe with old monsters.
I wanted to move away from that and take it more towards science fiction, or have more science-fiction stories and not have every story based on it being a variation of Invasion of Earth. I’d read quite widely science fiction and dystopian fantasy. Now they look fantastic, the Cyberman and so on, but in those days you knew it was an actor in a rubber or polystyrene suit, so to just keep trundling out monsters that were actors walking around in funny costumes was not my idea of what you could do with the show. What I did in a way was to deliberately and consciously divide up what I used to call ‘the monstrous element’ in the narratives so that they might not just be a monster, but there had to be something that was monstrous going on, and then something else, so there’d be elements that would add up overall to a kind of spooky and threatening feeling.
(Source)
As for Daleks specifically, note that they were inspired by pepper and salt pots rather than rubbish bins, as reported in a BBC retrospective on Dalek designer Ray Cusick, who recently passed away. The motivation was to have an alien that moved like a salt pot sliding along a table:
He [Cusick] explained that, in fact, the pepper pot detail came from a lunch with Bill Roberts, the special effects expert who would make the Daleks, when Mr Cusick picked up a pepper pot and moved it around the table, telling him: "It's going to move like that - no visible means."
"Ever since then people say I was inspired by a pepper pot - but it could have been the salt pot I picked up," he said.
(Source)
I believe you're thinking of the quote
No bug-eyed monsters
This initial suggestion to avoid weird over-the-top aliens was covered in the docudrama An Adventure in Space and Time. They initially wanted to focus on education and history.
This was abandoned in favor of using many aliens and monsters after the success of the first Dalek storylines.
Note: For the full Dalek introduction, start at 34:36
