Why and when did the interest for micro breweries and craft beers arise? During the past couple of years, the variety of beers found in supermarkets in Germany has vastly increased.
There is a number of beers that I remember having always been there, and a few have been added over time. But these don’t stick out much in price or flavour.

Recently, I heard the term micro brewery for the first time, and I noticed that large supermarkets have stocked up on many different (mostly regional) beers. Prices start at “slightly above average”, but some are easily ten times as expensive. A bottle of beer for 7 Euros? Not the most expensive.

This, and the fact that beer.stackexchange.com exists, and that many questions concern micro breweries and craft beers leads me to the questions:

Why this sudden interest in micro breweries and craft beers? When did it start?
I'm not sure about the German market for craft, but American craft can almost certainly be traced back to Frederick Maytag's purchase of San Francisco's Anchor Brewing in 1965. Since then, 'craft' or 'microbrew' grew slowly through the years.

A lengthy but interesting report called THE MARKET FOR CRAFT AND SPECIALTY BEER, A Market Intelligence Report, March 1997 has an impressive description of why craft in particular was able to keep growing, and why it wasn't labeled a 'fad':


  "There is also a floor under the craft/specialty segment. This is not
  a fad segment like packaged draft, dry, ice, clear, or perhaps even
  red. While growth in the craft segment will slow, it will not peak
  quickly and then lose share, as the fad beers have. The
  craft/specialty segment has firm underpinnings from homebrewers and
  other beer aficionados. Many of the homebrewers prefer to brew their
  own beer (done right, it’s even better than the best of the craft
  brews), but they often sample commercial brews to try unfamiliar or
  difficult-to-brew styles, and of course they’re top prospects for
  drinking craft brews when they are at a restaurant or brewpub."


That explains a lot through the 90's, but why the quicker increase in growth patterns in the last 10 years?

According to the Brewers Association (a US-based trade group): 


  "Between 2011 and 2013, 80% of craft growth came from new craft
  appreciators, the majority of which were in the 21 to 29 age group,
  and their impact is still muted. Lester Jones of the National Beer
  Wholesalers Association (NBWA) sees Millennials as not fully
  economically activated yet due to the impact of the economic recession
  and their struggle to transition into aging Baby Boomer jobs. This
  means as the economy improves we should feel the impact of the
  Millennials even more. The message here is the fastest growing and
  most influential demographic is also moving the fastest toward craft."


Pair this with the increased ideals behind "Trade-ups and premiumization", and you have people willing to spend a little more to gain an perceived increase in value and quality.

IBISWorld shares that craft beer has enjoyed a 19% growth in the past 5 years. I don't know about you, but that's incredible considering the economic woes of developed nations. 

It appears to boil down to a long, slow pattern of growth that has reached a massive generational shift in consumption which has caused a spike in sales volume, which in turn is pushing every store from New Jersey to Frankfurt to attempt to capitalize on one of the few growth industries.