Well, it does now. I just discovered by chance that a number of words in the March 2008 draft revisions happen to fall into this category. The entry for many, for instance, is as follows:
A. adj. (determiner). Designating a large (indefinite) number.
The word retains a more generally adjectival character (‘numerous’) when used predicatively (senses A. 1c, A. 2c) or after another determiner (e.g. ‘my many lives’). 1. Used distributively with a singular noun or pronoun (formerly sometimes with plural concord).
Much is the same, while other entries, such as every from the 1989 edition, are not marked as determiners.
Now, I'd just go ahead and take that old adj. out of there, but change is slow and I think the OED deserves kudos for going this far.