Old Who was not fundamentally about characters or characterisation.
At its best, it used characterisation as a way of expressing its actual concerns, which were narrative or semiotic or conceptual or thematic or mythic or political or satirical... or any combination thereof.
We know everything we need to know about who Kalik, Orum and Pletrac are, how they think, etc. for the pastiche/satire/parable/joke to work.
It simply isn't interested in how Kalik feels about his mother.
It certainly isn't interested in how the Doctor feels. Or hardly ever. Even when the Doctor goes home for the first time, we don't see him soulfully staring at his childhood haunts or standing in the rain over the grave of his deserted Mum. Instead, he gets caught up in a satirical political thriller that turns into a surreal duel and then an apocalyptic techno-melodrama.
Of course, there's plenty of characterisation in 'The Deadly Assassin'. Even minor characters have ways of thinking and speaking. Hildred is a brutal bungler. Borusa is principled in some ways, cynical in others, and has a sneaking admiration for his wayward ex-pupil, etc.
Worldbuilding, in the service of conceptual or historical or political ideas, needs this kind of characterisation. The more charged the concepts or history or ideas being explored, the more charged the emotion. New Who has never done anything as moving (to me) as "Binro was right." Meanwhile, Romana isn't pregnant or anything.
Yes, the Doctor looks sad when Jo decides to marry Jones. At the very end of a story about an evil chemical company befouling an environment full of unemployed people as part of a world domination plot by a mad computer.
When people criticise old Who for not paying enough attention to characterisation, they are often talking about the portrayal of reactive personal emotions, i.e. the kind that make people cry when they lose somebody they love.
This is to forget that drama can be equally compelling when characterisation consists of political or intellectual emotions.
The little sad sting at the end of 'Green Death' is effective, but the meat of the story is a conflict (albeit very broadly sketched) of viewpoints about ecology, technology and the limits of private power.
None of this means, by the way, that old Who didn't sometimes explore reactive personal emotions or neglect political and intellectual emotions. Because it did both, sometimes to egregious degrees.
Nor do I mean to suggest that new Who always neglects the political and intellectual emotions, because it doesn't. Well, it didn't used to anyway... before it came under the control of a man who can suggest visiting Marie Antoinette as an example of a nice day out, akin to a visit to the beach for any decent man, without even realising that he's just said something political.
Fundamentally, however, to criticse old Who for not paying enough attention to characterisation, motivation, emotion etc. is a bit like criticising a lasagne for not playing DIVX files. That isn't what its for.