I'm not @ghostieblu , but I do somewhat share their opinion, possibly for other reasons, or the same, no idea, so I'll give you my point of view:
First, I really, really like to see casts with LGBT characters. It's very important to me because I grew up before the Internet, at a time where it was very difficult to find anything I could directly relate to.
Now, sometimes the way such casts are introduced bothers me, and I have this same feeling of 'just for the sake of it'.
Because as much as I like LGBT representation, I don't like to have people presented as their sexuality/gender identification. It's only one part of what defines them, it's not all what they are as an individual. I want to learn that aspect of a character, only in a way that makes it logical for me to learn that. If that's the first thing, or one of the first things I learn about a character, when there is not reason for, I really don't like it. Now if it's the first thing I learn because, for example, 2 same sex characters are presented as being a couple, that's fine, even if it's not part of the story. But I don't want more focus on them and the fact they are a couple that if a straight couple was presented.. unless.. it has a purpose in the story.
What I mean is that I feel that pretty often, although their purpose is showing LGBT people as average people doing average things (which is great), writers/artists often singularize them in the way they are presented, a way that would not be done with non LGBT people. And that bothers me.