Was it a slow process?
I just want to jump in and say that beer is not, and should not be, exclusively served cold. Different styles of beer are best at different temperatures - for example an Imperial Stout or a Double IPA should be served "warm" (14-16℃), an IPA or a Saison should be "cellar temperature" (12-14℃), or an American Pale Ale or a Pilsner should be "cool" (8-12℃).
Only beers you don't want to actually taste should be really cold. Mass produced, cheap beer is served ice cold because that hides the fact that it tastes like arse, rather than because that is the temperature beer "should" be. If you go to nicer bars, or buy boutique beers (and follow the instructions that are probably on the label as to drinking temp) a lot of the beer you drink will be at, or only slightly below, room temperature.
Hopefully our sub's alcohol expert will stop by, but meanwhile, here's an old post to get you started
As vontysk points out, beer aficionados (geeks) rightly realize that not every beer should be or is served ice code, but the reality is most humans drinking a class of beer in contemporary times will expect it to be far cooler than room temperature so I think this is a legit question.
Widespread use of mechanical refrigeration only became common within the last 100 years so we can trace the practice to that era. That said however, in Europe especially, drinking establishments and those will a basement would often keep their barrels in a cellar and thus the beer could often be served "cellar temperature".