it is a very slippery slope that is best avoided. If you add the LGBT Flag, then people will ask for other similar Flags, Trans, A-Sexual, BI, pansexual. Ect. Then people will demand that their Identity/Ideology be represented too, and will throw a fit when they aren't.
And then you get the people who will call out DE for pandering to Minority groups, and blah blah blah, they will threaten to boycott the game for forcing ideology, blah blah blah. The Community starts to call each other names for supporting the side they don't agree with.
i mean look at BFV and the ****Storm they caused with the whole Ginger Cyborg Lady in their Trailer and how they responded when the community complained. Politics are bad for games, and the LGBT community is very politically charged.