To be fair to WOTC 42 and 41 are trash, 42SE is mediocre, and 1914 is a disappointment from a purely gameplay perspective. Additionally, Larry didn’t have a ton to do with Revised, which is one of the better entries in the series. And that’s not even getting into the depressingly bad spin-offs from the early 2000s (Bulge, Revised, Guadalcanal).
That being said, he deserves most if not all of the credit for bringing us A&A (both Classic and the franchise as a whole), AA50, and G40 (which as I said a few posts up is basically his masterpiece, war room be damned).
Re: Sales. I have no sales data to back this up, but I seriously doubt A&A, other than the original Gamemaster Edition, has ever been a serious needle-mover in terms of sales figures. It falls into an unfortunate grey-area of being too complicated for casual gamers (think stupid young people who will only play on their phones, or folks who think Risk is “too hard to understand”), while being too abstract for the serious wargaming crowd (i.e. people who play A World at War, Advanced Third Reich, etc.). Additionally, other than the abysmal 1941 edition (and possibly the Gamemaster Edition, but I don’t remember 100% so don’t quote me), the game has only really been sold in dedicated hobby shops and online, which definitely limits its marketability.
A&As main niche is WW2 history buffs, which is a relatively small one in this day and age. I’m not making excuses for or defending the poorly thought out decision to put Zombies in the game, but there’s a clear reason why the decision was made. If you don’t like it, just don’t buy the game. There’s always War Room (Larry’s project, due out later this year, although I’m not sure you’ll be able to get a copy if you didn’t back the kickstarter) and the Global War line. Both of these have their own sub-forums.