The clan tartans I wear are of my own clan. I won't wear the clan tartan of my Mom's maiden name, nor any of the other tartans in my bloodlines. Why not? I'm not a member of those clans, and I don't identify with them.
As far as corporate tartans do, I'd prefer that they be original, and not draw on clan tartans.
I do like the district tartan concept. It means I can have a few additional kilts, and I'm not as strict on myself with regional tartans as I am on clan tartans.
What anyone else chooses to wear is up to them, of course.