I don't really hear Castro being brought up without the context of his race, which may be due to a lack of charisma or talent in public speaking. Booker on the other hand is a much better speaker in my opinion, and his race isn't inherently that important of a factor.
I've seen many bring up Castro as charismatic and a good speaker I think his race being brought up has more to due with Trump
His race was being brought up long before Trump as a parallel to Obama, and others may think he has charisma but I don't personally feel he's anything special.
Then may I ask why you chose the username Castro2020? Were you talking about Juaquin, or did you mean it to be ironic?
I think I had been browsing the Election What-ifs? Board for a while before I registered, and I mainly meant it to be predictive of the future, rather than indicative of support. My early thinking, before I fully jumped into the rabbit hole of deep political analysis, was that Clinton/Castro would win in 2016, Clinton wouldn't seek a 2nd term, and VP Castro would run. I decided to shed the 2020 part of my name a while ago and just go generally by Castro, not referring to any particular person but myself.