One of the reasons why I'm not playing anything before the renaissance these days is that since rule sets of the last decade or so have clearly shewn that the wargame without book-keeping or individual casualty removal is possible and much more streamlined, I can't stand the idea of reverting to the old stuff. But DBxing light troops, while fine for small numbers of skirmisher types who are there to support, distract, pursue, and generally irritate, just don't reflect the slow but ultimately deadly trickle of casualties which are essential to many ancient and medieval armies. In DBM, only a fool would try to win using Parthian or Mongol tactics; which, since those were definitive killer armies on home ground (for Mongols, this means most of Eurasia, I realise), is a real weakness in the rules.
Apart from that, shooting circles, wedges, expendable first-round weapons, and shielded/non-shielded targets are just not reflected in those rules, nor can I see how most of them could be, unless one were prepared to discard everything that otherwise makes such rulesets attractive options.
Anyone want to throw in ideas, however silly?