Personally I don't think Salinger was a great author. "Catcher in the Rye" is a bit redundant and cliched at times. Nevertheless, his reclusive nature probably added more cachet to his work than the work itself has warranted. So the better question might be "do authors who recluse themselves add or detract from the intrinsic quality of their works?"
The other great recluse of the 20th and 21st centuries is Thomas Pynchon. So far, besides some "spy photos", he's flown under the radar. Unlike Salinger, his many works stand on their own as exemplars of modern American fiction in the eyes of a wide range of critics. I often think that Pynchon's reclusive behavior has not changed the intrinsic perception of his work, but rather has elevated a desire to grasp the author's critical appraisal of his corpus.
In short: reclusivity may or may not benefit authors, depending on the public reputation of literary works.