For the amount of passion it seems a lot of animators put into their work it seemed more interesting that there was an artistic decision about how the audience will connect with their character to explain the style and not that it was just too difficult. But that may very well be the case and the other is just a convenient side effect.
That doesn't look too detailed, but imagine drawing four of those every day for a year without weekends. 365 x 4 is about equal to 24 x 60. Congratulations, you've created a minute of footage. To make a feature film, you'll spend a life.
I guess Disney-style animated characters occupy a kind of sweet spot. They are carefully stylized to look good enough that adding more detail won't really make them much better, and simple enough that a large team of animators with top-down planning can make a complete movie in a few years. Japanese anime has slightly more detailed characters, at the cost of having fewer frames per second. If you want a lot more detail with good enough framerate, you need more money than your audience is willing to pay.
Also reminds me of some of the points made in Understanding Comics[0]
"...Another is the universality of cartoon imagery. The more cartoony a face is, for instance, the more people it could be said to describe."[1]
[0] https://en.wikipedia.org/wiki/Understanding_Comics [1] http://www.proprofs.com/quiz-school/user_upload/ckeditor/und...