[Evisse the Blue]

They are not ‘pure’ manifestations of natural ‘good’ who can be corrupted, but – like ‘us’ – regular and normal people who are capable of both “magic” and “art”, “Rules” and freedom, “order” and “contradictions”, generosity and possessiveness.

Yes, but they do have a degree of innocence that separates them from other races, which makes their 'corruption', or tresspasses, if you will, more significant than a Man's or an Elf's. In their own basic way they have created a paradise in their Shire, which is unequaled by other races they are an amalgam of, so if only in that they are special.
I agree that hobbits are somwhat the 'anti-heroes', (not possessing the qualities one has come to expect in a standard hero). Tolkien plays with our mind in describing them as totally plain, and simple-minded in the beginning, so that later on in the story, he may unravel their qualities. It's like he's giving us a lesson: "Wait and see!" It's a lesson good for life, too.

EDIT: 'crossposted with you guys.

Mount Doom as the anti-pipe

Whoa! Soon you'll be saying that Tolkien anticipated the dangers of smoking!
But seriously, I for one think that all the points in common you stated here are grounds for contrasting the hobbits with the bad guys, rather than serve to show how they resembled each other. That is, there is a qualitative difference, not only a quantitative one.