1. I can understand the reasoning presented by the community, sure. But at the same time I can't say I agree because it sounds way, way, too close to discrimination for me to get behind. Saying a person isn't allowed to portray a certain character and do a highly respectful and dignified portrayal simply because of the arbitrary differences of their circumstance harkens way too much back to the time where certain characters wouldn't be allowed to appear on the screen with other characters due to such arbitrary differences. If a trans-actor or trans-actress gives the better performance of the character, then by all means they should portray that character. But if there is an actor who captures the character more, their spirit more so then their physical attributes, then that person should probably get the role. It's like if white people were denouncing the marvel movies nick fury because the nick fury in the comics was white and in the movies hes black.
I don't actually agree nor disagree with whether or not someone like Jared Leto should be a trans* character, mostly because until 37 seconds ago I was completely oblivious to it as a topic.
I can see ocean's perspective, however. As an analogue, however, it wasn't *too* long ago that white people commonly used to portray other races. Things like black face or Mickey Rooney's Mr. Yunioshi. Taking an extreme example just to sort of illustrate: I think Daniel Day Lewis is an excellent actor... would he be the best candidate for portraying Martin Luther King Jr.? Going waaaaaaaaay back, women couldn't even be actors... but I don't think we'd want Patrick Stewart replacing Cate Blanchett as Elizabeth! 
At the same time though, I can agree that I'm not sure if it's absolutely necessary either. Is it bad that Leondardo DiCaprio plays a person with a handicap in What's Eating Gilbert Grape? Can a straight/gay man not play a gay/straight man in a role?
Another thing to keep in mind, too, is that discrimination may be internalized and implemented institutionally, even with no overt fault of those that perpetrate it. There was a study done where professors, both men and women, rated a potential research applicant. In the experiment, the application was identical for all people, except some people received one that had a woman's name, while others had one that had a man's name.
(NOte: Statistical significance, since I use the term, denotes "The difference is significant enough that luck/random chance most likely is not a factor." Not "this is important).
There was no stastitical significance in how the professors rated the applicants, regardless of being a man or a woman. That is, the deviation in scores between men and women professors was small. The scores on the applicants however, were different and statistically significant. Regardless of the assessor being a man or a woman, the applicant scored better when the name was a man's name, across the board. The applicant, with a man's name, was considered more hireable, more mentorable, and more comptent. Both male and female assessors also offered the man a higher wage.
Now we can't say WHY this may be the case, and more research is almost always useful. But it does give an interesting "Huh!" It also lends the idea that perhaps even women internalize some of the expectation discrepancies. This tells me that there may be a a more systemic bias that affects people subconsciously, causing them to rate an applicant different based on their expectations on gender. So I do hesitate to say that it's discrimination outright if a trans* person were preferred to depict a trans* person in a show. There may be systemic biases that cause us to THINK that a person is better qualified than someone else, when perhaps that technically isn't true. I do believe that objectivity is not an easy thing to have as a human being.