I would suggest refraining from interrupting their television time. I'd be annoyed if people kept yammering how marvel movies are unrealistic or something. :c)
Instead, try and leave such until the end of the cartoon. Ask them what they thought of that - what they did or didn't like. Anything that struck them. That is true freedom of thought in action. :c)
Otherwise they might be inclined to hide their true opinions from you.
However I do feel that you are right. the production-friendly animation/ storytelling methods of today aren't totally a step forwards from the style of a couple decades ago - and some would argue that its quite the contrary.
That's a good suggestion but I will say it's harder than it sounds. Watching some of these shows and staying quiet can be torture when they have such a bent world view. It's very true that a suspension of disbelief is needed to enjoy these things though, finding that balance is the goal I'd say.