Design isn't about us liking those tastes or not. One part is about ergonomy of course, and the other is about looking up-to-date. Just watching the colors of a website/app, you could tell which year it was made and whether it's well maintained or not.
One could ask "Why do we define a fashion, given this fashion costs heaps to everyone in the industry and isn't necessarily nice or ergonomic". Remind that for every free land, humans will populate it, define rules and laws and regulations and fashions and richness, and whether it is good or not it can only go forward, with more laws, regulations, fashions and richness.
And taste only tells how close you are with society and how distinct you are from uniformity. http://xkcd.com/915/ So you must both stick to the trend and stay peculiar. The trend is defined by very few "haute couture" designers in the industry and we're only adapting it to our clients.
