If you're in the brew bar or brew pub or microbrewery/restaurant business, you are in the hospitality business.
The customer is always right. And a successful business owner who is chasing the profits is going to give the customer what he or she wants. An artisanal brewer isn't necessarily going to give in to that pressure and would likely be content with a much smaller following (and profits, if any).
We love beer: good, craft beer. But, we're enlightened and adventurous. Most people aren't. As much as it pains me to say this, my wife doesn't like beer. Even at my recent once-in-a-lifetime tapping party at the local brewpub (when my award-winning recipe got scaled up on a commercial system and brewed for public consumption)--my lovely and supportive wife was drinking ...white wine.
And, because of limited demand, some brewpubs just can't move certain beers quickly (e.g., stout) compared to house faves like pale ales or IPA's.
Most brewpubs make more money on food than booze. (Not to mention that the alcohol licenses are cheaper in my state if the >51% food / >49% beer/booze rule is intact). The microbrews might be what gets some people in the door, but the ambience, novelty, and food is what brings along the company and pays the bills.
I can be a proud man and a patriot. If I ran a brewpub, and if I could remain in the black, it would only be the American microbrews on tap (my own, then other local, regional, and nationwide beers). Of course, I'd probably end up with a special "reserve" list of (domestic and foreign) beers for the beer snobs amongst my clientelle who are into style calibrations.
Brand loyalty often breaks on price--you may wish to sell your lager or kolsch for $4/pint and a bottle of BMC lager for $5. Again, you're in the hospitality business; you're giving the customer what they want (product), but not the price.
As a customer, it would not sit well with me if my wallet and I walked into a brewpub and my bartender, brewer, or brewpub owner were dismissive, rude, or condescending to me about any beer requests. My money doesn't stink, and neither should your attitude towards customers.