I remember wondering the same thing a while back. My girls loooove cooking with me, and there is so much to talk abut and show them, even if it's not quite as traditional.
Even with a TMX, you still have to teach them how to:
Follow a recipe
Count and measure
Crack and separate eggs
Chop things up
Taste and amend if not how you like it
plan ahead
Test if somethings cooked properly in the oven
Improvise if missing an ingredient
So I think our kids are definitely better off with a tmx as they're getting better food, and are learning about food, rather than opening a box and using a microwave.