I'm a lesbian in my mid thirties. It's not my chosen way of describing myself, and I'm cautious in using it for two reasons -
- Lots of (LGBT) people still find it offensive, with good reason
- It has IMO a shifting meaning so often doesn't aid clarity.
I recognise what people are saying here about it seeming to be a handy identity for people who appear to be straight and not trans but who want the cool points. Having run the gamut of homophobia and lesbophobia for many years now, the idea that there are cool points makes me roll my eyes hard. I also suspect that for many/most teenage girls, lesbian is still a difficult label to assume and present with.
A bit earlier than this, I experienced it as a reclaimed word which strongly connoted a certain set of gay politics - queer theory stuff, before queer theory became so widely discussed in the mainstream, and also lots of gay liberation type stuff which emphasised the shared struggle and overlaps of L/G/B/T people.
I know people who have lived for decades on the boundaries of lesbian/gay/bi/trans, for whom I think it can be a helpful way to capture that. I do think this is different from the wistful straight people who want to perform their queerness whilst also benefiting from societal approval bestowed on their observably-straight relationships. Eg people who are female-bodied, sometimes passing as male but not strongly or consistently identifying as trans men, who have relationships predominantly with other women - it's not on me to tell them they need to call themselves a lesbian, although obviously they qualify for this label (maybe this is where I'm differentiating them from the 'cool points' people).
Finally, it's helpfully more amenable to verbing than lesbian is (or even bi, gay, homosexual etc). So it's easy to talk about queering an aesthetic or a dynamic or whatever, and I'd theoretically use it in that context. I could rework the whole sentence to use some version of the word 'lesbian' instead, but queering is a very usable and well recognised term which works for me.
I think it's a fraught term, and would not recommend straight people adopt it as an inclusive term when they (occasionally) need to discuss LGBT people as a group. But I also know from experience it's very avoidable.