Sounds like I agree more than disagree with you as to what the nature of science actually is, but a couple finer points of difference regarding 'intelligent design':
Where they differ is on how to explain the evidence—what model to use.
Have ID proponents offered any model at all? I don't see one at all - only statements of belief as to the adequacy or inadequacy of existing models to explain what is still unknown. What's more, they dump the burden of 'proof' on others, instead of offering any positive evidence of their own position.
The ID people believe that the natural selection model is inadequate to explain the available evidence. I do not know whether they are right; however, I think it would be unwise to dismiss them out of hand.
I might be inclined to agree here if the ID movement had ever been anything other than disingenuous from the get-go (i.e. the Wedge Project). The ID movement, as it is now known, is not an attempt to expand scientific knowledge, but rather, to sabotage it.
Of course evolutionary theory still has a lot of work to do (just about all theories in science do) - and healthy skepticism is an important part of science, but institutions like the Discovery Institute and other promoters of ID are only trying to use the gaps in our knowledge to break down people's confidence in the veracity of all scientific knowledge, even where there is little to no doubt - a very unsettling trend indeed; and I don't think groups like the Royal Society are out of line to take a position on this.
There has been opposition to science for as long as there has been science, and always for the same reason, using the same arguments.