First, I would like to say that I completely agree that labels are not necessary and really should be used to the level of comfort of each individual.
Personally, I don't believe labels are very accurate representations of who or what any one person is. I think that labels allow individuals to more smoothly integrate into and function within society. Some people are more comfortable identifying as lesbian or straight because with that comes an entire set of behaviors, a language and a group that you are placed into by default. This is comfortable for many and quite possibly necessary for some. It is easier for someone to comprehend your sexuality and or gender if you place it somewhere in the gender dichotomy. We have forged a few labels in between male and female, but only in relation to their relative distance from cis.
In my opinion, I don't see how one label could accurately describe how your individual heart sees another human being. What word could describe how you love?
I personally identify as bisexual. This label is merely used as way to relate with my environment. My soon to be spouse is transitioning and I at one time identified as lesbian. Now, I see that it doesn't really matter to me what he identifies as, because my heart loves HIM for what he is as a whole. My heart doesn't love as a lesbian, bisexual or straight individual. My heart loves as a human being who is purely devoted to another.
Sorry for rambling, I am just really enthusiastic about gender studies.

Hope this helps!