Native Americans have been delegitimized for 500 years. It's easy to make a racist joke about a smaller population and say "it's not a big deal." It might be just a "stupid sports logo," but it is still demeaning. Also, if the logo doesn't really mean all that much (i.e. stupid sport logo) then it should be easy to replace.
Atlanta didn't have much of an issue with dumping Noc-A-Homa when they needed to. Maybe it's time Cleveland does the same.