Why did they add a "Q" (for "Queer") to LGBT? Isn't that an insult label?

This is what I understand:

L = Lesbian: Women who are attracted to women.
G= Gay: Homosexual men; men who are attracted to men,
B= Bisexual: Men or Women who are attracted to BOTH sexes.
T= Transgender. Men or women who do not identify with the sex of their birth, but with the other sex—irregardless as to whether they have had sexual reassignment surgery, and irregardless as to which sex they are attracted to.

Now, the “Q” (Queer) label used to refer to homosexual men, or occasionally transgender men or boys with effeminate traits. But it was never a ‘nice’ thing to be called. It was like the designation ‘faggot’ In any case, it seems redundant with the other terms of the LGBT banner.

Androgyny, Hermaphrodites, and asexual or non-sexual are not covered

I personally do not like using the “Q” banner because it is an insult. But it seems to be coming into vogue.