Oh
Finwe, you're practically Snow White. Accept it.
Nah, seriously though, I think there is a huge leap one must take from Bilbo & Frodo's characterizations all the way to Asperger's Syndrome. If these were real people, I might be willing to hear you out. But in the literary context, the logic doesn't stick.
Theron has got it right when he says that the emergence of colourful diagnoses can be traced back to people not being willing to raise their own darn kids. They want doctors, teachers, policemen, politicians, radio and TV to do it for them.
A number of historians and literary critics, as
Sharon already touched upon, will also use some sort of diagnosis in order to "analyze" a person's work in the context of their life. I once read a vulgar biography of Chekhov that compared his sex life to that of a cheetah and said it was a result of a "disorder". I'm not one to cringe at such things normally, but the author's style betrayed this claim to be mostly sensationalism. "OOOOOH look how dirty one of the greatest writers in the world turned out to be! OOOOOH! How shocking! How provocative!" Whatever. The greater majority of writers are "dirty," and unless you have something original or captivating to say on the subject, you end up sounding no better than a tabloid journalist, and possibly even worse, considering the fact that those people at least aren't pretending to be anybody else.
The point I'm trying to make that we, as a society, are beginning to sound positively hypochondriac when we attempt to label everything a disorder or a disease or a malady. Furthermore, there are people out there who really are seriously afflicted, and they get lost in the jumble of other voices, each one demanding special treatment because of this or that. Sad.
Personally, I don't think that some sort of Asperger-like affliction is what unites Tolkien fans. Maybe (whether only on the inside or full-out) we're just dorks.