That's a great question, and the differentiation here turns rather subtle. These still are considered scientific, I think, because the full explanation is within this universe, and may be further investigated by science because they are subject to further natural laws. There is some assumption among us all that intentional intelligence is a "given" phenomenon which occurs in our past (archeology), present (forensics), and may be "out there" (SETI). Even if intentionality can't be understood only in terms of natural law, and intelligence is hard to pin down, our experience of them allows them to skate by as "givens" within this universe.
Careful philosophy can certainly argue, as you and I have, that ultimately these are no different from ID arguments. But some want to draw a firm boundary within this universe.
I don't think science can rule out natural explanations for life. It's job is to describe it and find the natural causes.
However I would agree that since science has shown us so much, the data sure doesn't look right, if mutation and NS are the only method. And some people seem to have remarkable faith, certainly way beyond mine, that mindless molecules can solve outrageously complex problems.
I think ID is criticized for both legitimate and illegitimate reasons. Even sometimes for the issues you raise, ID proponents can make the arguments in a lousy way. Yet if they made them perfectly, they would still be criticized from some quarters.
Yeah, me too. Then again, people accused Jesus of having a demon.
But as Teddy Roosevelt said, "It is not the critic who counts..." I love that you are in forums with people who don't agree with you, trying to ferret out their perspective, keeping prodding, keeping your cool! That's what I'm trying to do and why I'm here. And I really have learned a lot!