I'd agree that the ensemble casts are a good thing for Star Trek but it's sad that everything has to be discussed in a committee - just like the real world.
We've gotten ten big clues on the Doctor, but we've only gotten to know one person... even then, we're not much wiser as to who or what he really is.
Then there's the Doctor Who Ensembles... The Brigadier, The Master, The Timelords, Davros, Possibly the Rani...
and a few companions too... Benton, Yates, Ian and Barbara, Jamie, Sarah, Tegan, Ace, Romana, Leela, Rose, Donna ... even... gulp... Adric.
They all had fairly plausible motivations - even if they didn't really have much movement in terms of story. Still, you can't tell me that Chekov went anywhere really....