I don't know. Maybe a beer store isn't the right place to sell brewing ingredients. Like a bakery selling flour.
I will take a different tack on that, though...
A homebrew store selling beer is a great idea.
Locally two of my nearby stores [O'Shea Brewing and Windsor Homebrew Supply] also sell craft beer. O'Shea has been doing so for as long as I've known of them, they're the place to get special kegs of craft beer, and they sell a lot of rare and hard-to-find craft beer. Windsor is newer (recently celebrated 2nd anniversary), just expanded their store and added commercial beer. Again, it's more of the rare and hard-to-find stuff.
The LHBS business isn't easy. Margins are thin, there's a lot of competition online, and in highly populated areas like where I live, the LHBS actually are also in competition with each other.
Adding a second revenue stream (craft beer) is helpful to the bottom line. Having that as an additional reason for people to come to the store--where they might decide they need something brewing-related--keeps you more relevant to your customers.
Another local store to me just changed management because the owner was forced to get a 9-5 job. I just met the new owners and they were saying they "hope" it picks up. While the store is w/in 2 miles of my house, I fear they're not going to survive unless they do more than "hope". If they sold craft beer I might go in there more often than I do now, and there are times that I might go to one of the other stores if convenient because they have supplies *and* craft beer.