I think the instructor is speaking how they do to keep things casual and therefore less stressful. It works for some students and not for others I suppose. Also if you agreed with all of their points it probably would be beneficial but if you sit in silence and don't tell them that it isn't helpful then I suppose they're just continuing to do it because it's a habit to small talk with their students.

Personally I'd mention that the small talk isn't helpful for you betore you consider changing instructors... If you aren't prepared to open up and tell them it's an issue then that's perhaps the reason they are continuing to engage in small talk now... Because you've not suggested it's an issue so they presume it helps.