Who cares about the color of people's skin?
The president and is a big deal, the people he listens to is important to many in this country. The lack of AAs and Trump's behavior is a worrying sign to a lot of people that he doesn't give a rat's ass about African Americans or minorities in general, and is even hostile to some of their interests.
I really feel like this should be self-explanatory. America doesn't exactly have a direct line to Trump
(Twitter is more like Trump's digital toilet seat that he sprays fecal matter onto America from), so they look at everything he does and says and those around him to interpret his intentions/thinking.