" But you cannot apply such a theory to life on Earth."
Your post makes valid points, but ultimately ID & Creationism both rely on a 'God' (an Intelligent Designer). To date, proving the existence of such a super being is impossible. Thus, unprovable.
Personally, I tend to lean in the 'assisted evolution' direction.
I wish that more anti-evolutionaries would forgo all vaccinations and other medical responses to the rapidly-evolving flu viruses, etc that pop up each year.
That "ultimately" is precisely the problem, though. You have no way of assessing it -- for it to be valid you must make assumptions such as those I described above.