Not just mixed drinks: Prohibition killed decent American beer & wine as well, and led to decades of industrialized, homogenized mediocrity that we are still recovering from.
Go into any neighborhood liquor store, and in addtion to the Big Three and the other inexpensive pale lagers and pilsners, you'll also see something from one of the major craft breweries (Samuel Adams, New Belgum, et. al), -- a couple amber ales, and at least one pale ale or wheat ale. Go into a larger liquor store, and in addition to the above, you're likely to find beers from other craft breweries local to your region, all of them offering various ales and lagers ranging from very pale and light to very dark and heavy, and plenty of points in between.
There's good stuff to be had. You just have to be willing to consider beer to be more than cheap pale lager, and to go looking for it.
The craft brew scene has exploded only in the last couple of decades and most microbrewers are comparatively new to the craft. Hopefully a broader variety of styles will become better represented as brewers gain experience and try to differentiate themselves from the overly hopped masses.
At present, the lion's share of my favorite North American microbrews are from Quebec. I don't know why, but the brewers of that province are hitting it out of the park right now.
IPAs are relatively easy to get right, but subtler styles like pilsner require more precision in the brewing process.
Now I'm seeing far more hoppy stuff around, but I'm also not goign to bars in Seattle anymore.
Beer Advocate lists 618 Doppelbocks: http://www.beeradvocate.com/beer/style/35/ and, taking a quick look down the list, it appears that at least half of them seem to be made in the US.
Hah, well finally I am validated. I was an anti-IPA snob when IPAs became all the rage. People would tell me how great this beer is, soooo bitter. Which to me is like drinking 80 proof vodka and claiming to taste the undertones of grains in it.
It sort of became like a badge of beer connoisseurship -- the more bitter you liked them the more you knew about beer.
Anyway, my favourite are wheat ales but also like stouts.
It is not all about taste. Marking is 50% of it. For example Pabst Blue Ribbon is an amazing story. It went from cheap crap beer people cooked with to hipster signature within 5 years or so.
It is the same crap but marketing turned it into cool "awesome" drink that every tight-jean, flippy-hair, messenger-bag carrying self-respecting hipster would want. Or was 3 years ago and now they are drinking something else...
Anyway, a lot of it was due to very clever marketing, product placement and sponsorship.