the devs are hired to make products that people will buy. Though you can argue its the development teams "art" its not always the case. I think yoshi is kind of half way in that aspect, he is making it so it will sell, giving us what we ask for, but hes trying to do things he likes too.
Of course you cant say this about all devs, some of them are in it to make money ::cough same call of duty every year ;;COUGH