It's better to have them say something, other than nothing. Isn't it?
I don't think anyone wants them to say nothing, this isn't a light switch issue.
My observation is that Bethesda has made the public too talkative, when they've only a few lines to say for the most part. I'd find it far more realistic if NPCs just nodded at me most of the time in passing, with an occasional "good day", once in a while or maybe a scowl if they were guards and your bounty levels were not exactly criminal but still high enough to stretch their trust of you. I'd rather trigger their dialogue by my initiation of it, not just having it blurted out at me.
The shop keepers should have a simple greeting, their scripted "colorful" greetings are fine, but the efffect is totally losst when different voices on different characters still say exactly the same thing. "Me... I call them treasures!" should not be everyones modus operandi !
Personally I've found the quieter companions to be the far better ones. Illia in particular can say a lot with just the way she is animated. Your imagination tends to make the story behind her gestures and facial movements. RPG anyone?
For the future, I'm wondering if Bethesda shouldn't concentrate on creating 5-7 very well crafted companion NPCs, rather than the hodge podge were all House Jarls are saying the same things, and others such as the mercenaries share various lines as well. There is some delineation, but there really needs to be much more.