As a transhet person, I find it important for a word like "queer" to exist. Not all LGBT people are gay, or even a sexual/romantic minority, and "LGBT" (and its variants) are a mouthful in spoken conversation, so "queer" is a great umbrella.
Isn't that the literal definition of the LGBTQ+ community?
There are straight trans people.
That is a sexual minority.
Nope, heterosexuals are not a sexual minority. They're a
gender minority. What makes a straight trans person queer has nothing to do with their sexuality, as being heterosexual isn't queer. Being transgender is queer, so that's what makes the straight trans person in question queer.
The definition of being queer or LGBTQ+, at least as far as I and most other people believe, is being anything that isn't heterosexual
and cisgender. A cis lesbian and a straight trans dude would both fit the bill for being queer, even though the first person is cisgender and the second person is straight.