As homebrewers we now have available to us a multitude of yeast strains that are specific for the numerous commercial beer styles. Using the proper yeast is important if you want to call the beer 'to style'. If you use US05 for you're German hefeweizen it won't taste like a hefeweizen but will fall into the american hefeweizen catagory which is fine but shouldn't be considered or refered to as German.
This leads me to explore what has been a growing concern in my own mind. I've sampled beers from many brewpubs that use the same yeast strain on a whole string of the varying styles of ales that they brew, sometimes even using this same ale yeast for their lagers. This results in beers that are called one thing but because of the yeast selection do not live up to the name. The beer may taste fine and I have enjoyed many on their own merit, but I always leave with a nagging desire to suggest to someone (anyone) that the beer be labeled correctly. Besides being rude to the brewer and appearing anal retentive, is it wrong of me to ask for this kind of accuracy?
For instance, a brewpub in a nearby town that I occasionally frequent has on tap what they call an 'English ale'. It is in fact not an english ale because they don't use an english ale yeast and so the resulting beer doesn't taste like an English ale. I suspect that it is fermented with Whitelabs 001 or Wyeat 1056 based on the samplings I've done in the past. My suspicions about their limited use of yeast are further supported after trying their other selections from the line up of beers on tap with names ranging from British pale ale, Irish dry stout and Pilsner that again have the same yeast characteristics dispite the obvious difference in the grain bill and hop regimen. These beers are unable to live up to the names applied to them.
Obviously, a small operation like a brewpub needs to be concerned about costs and one way to do this is by re-using a single yeast strain for multiple batches of beer. By re-pitching over multiple generations, transfering the same yeast from the pale ale to the English ale and then on to the stout results in huge savings for the brewery, so it's hard to hold this against them.
They also need to move a lot of beer by producing beers that are popular and easy to drink and appeal to the general public which means not only of good quality and flavorful but also produced quickly and available at the tap as soon as possible. As a result, they are less inclined to brew beers that require longer fermentation periods or the expense of a lot of different yeast strains. It's no surprise that you don't often see sour beers on tap or beers of unusually high alcohol that require high gravity performing yeast and long lagering times or blends of yeast that include bacteria.
On the other hand, I suspect that it could be possible economically to produce quite a number of styles of beer with just four types of yeast on hand. For instance, a variety of English ale yeast would be appropriate for not only English or British styles pale ales but also a wide selection of Irish, and American ales. One lager yeast for all styles of lagered beer. A German hefe yeast for all wheat beers and other ales that benefit from a phenolic character or maybe a Belgian strain to produce a golden, or tripel style.
Having an assortment of taster samples in front of me that vary in color, texture and aroma is an enticing vision that gets my taste buds to stand up and pay attention and it's all the more gratifying when the flavors are unique because of the unique strains of yeast as well as the grain and hops used in brewing them.