It's fun to try to imagine how these make sense in timeline order, but from the horrible shrinkage of velour (and future productions refusing to touch it*, even for flashbacks/era matching) to the loss of the ability to make the collar for the monster maroons and giving Patrick Stewart a back ache, it's mostly all been about production constraints.
*: Probably due to now having union rules requiring the uniforms be laundered, which is what shrinks them. I think they changed size with every cleaning?