Should GLB always be thrown in with the T in mainstream culture?

DISCLAIMER: I am NOT saying that the gay community SHOULD try to exclude those who identify as trans in any way.The thing I've been thinking about is that over the past 8 years or so in culture and now more recently in business, education, and a lot of areas, sexual orientation is being thrown in with gender dysphoria oftentimes in discussion with the LGBT acronym being used for convenience. While I know not all those who identify as transgender fall within the gender dysphoria diagnosis, I feel there is a fundamental "one of these things is not like the other" thing going on. This goes both ways for GLB being thrown in during discussions about the T and while I understand that there are cultural similarities of historical hardship faced by both communities, I am not sure this makes sense.They are two very different categories- one is about sexual orientation (LGB), the other is still technically considered a mental disorder by the majority of the psychological community. Now over the past few years, major progress has been made with achieving much more legal equality, social acceptance, and dignity for both groups of people all across western countries, but why should there be a T in LGBT? Clinically/psychologically/etc, they are two different things that are not related by subject. Culturally, we are both historically disadvantaged minorities, but we don't really see other groups getting lumped together in the same way I don't think (like being disabled with being asian american or something).So what is your sense on this? Do you think this is as it should be? Do you think it doesn't make sense but is not worth changing? Do you think it is but are too fearful to be called transphobic or bigoted to offer this question in public?