I too get really confused when I see how angry people can get about these things. I sometimes wonder if its caused by a lack of self-awareness or perhaps fear caused by their own non-cishet inclinations.
It’s also interesting how much overlap there is in bisexual and trans experience. Obviously, being cis and bi is different from being trans, but we definitely have a certain commonality in the way the queer community has handled us in the past.
I like to say that bi and trans folks are natural allies — both in the fight to be recognized as valid, and due to the bare fact that bi folks tend to be pretty darn accepting of trans folks and vice-versa. In fact, a not insignificant part of why my wife and I are still together — even after I transitioned — is because she’s bi and was able to see me in another light as valid.
Someday, the “B” and “T” of “LGBT” will be a much bigger and more accepted part of queer culture — we just have to keep pushing.