The 'in' naming trend in Hollywood is to give girls boys names. I don't mean calling a girl Charlie rather than Charlotte, I mean calling a girl 'James'.
Personally I don't have a problem with this. It's just a step on from Charlie.
Re parents giving a second name I always felt for my parents when my brother changed his name. A name is a gift from your parents and it helps to shape your life whether you realise it or not (see freakonomics). It can say a lot about your background, your parents political outlook and your parents aspirations and hopes for you. You can also gravitate to things that echo your name. It's something that helps form your identity.
When my brother changed his name, I felt it wasn't just him changing his name but also a rejection of my parents. It was a rejection of his hertiage and things that meant a lot to my parents. It was outwardly saying that their contribution to his identity was null and void and needed to be destroyed.
So I can see why getting your parents to rename you might be appealing. But I also think this is about using power over parents too. The whole point of a name is highly connected to identity formation so asking parents to rename when you are an adult is fraught with pressure. These are parents who have already effectively been told they have 'got it wrong' so I can not imagine what the pressure is like to rename someone. This name will not reflect the time someone was born but the trends of the time they were renamed (you can see this in soaps where new characters, particularly ones in their twenties tend to have names which reflect the latest baby name trends not the trends of the time they were supposed to be born). It won't reflect their choice and innocent and idealistic hopes for their child as a blank canvas. It will ultimately be about what they think their child will like not about what they will like. In this sense it does very much reflect a changed power dynamic where the parents are no longer the authority nor respected.
Ultimately having see this play out, I think it really made me think name as a gift more than I ever felt before. It's a gift that should have that understanding of the love that went it choosing it and what it meant to the parents when they picked it. It's a reflection of their life and a connection to them.
I felt this particularly acutely when I had DS. When DH and I were choosing DS's name we felt a huge amount of pressure and responsibility to 'get it right'. It certainly wasn't just a name, it was a really personal gift. I feel now more than ever that people who change their name need to understand this and how it may cause pain to change a name. This also has a particular effect on siblings too as parents name siblings to have names that 'go together'. When you are growing up you get referred to as a singular entity a lot. For example where would Topsy be without Tim? Topsy and Esme kind of loses something...
I don't think people need to formally change their names to reclaim and assert their own identity. People can go by nicknames or middle names or the gendered opposite to their birth name, to maintain the importance of that gift.
But as I say I do feel that the whole point is precisely to put two fingers up and about power and control and that's why it's regarded as such an important stage in transition. It's a statement - both in action and potential shock value. It's a statement of intent and of new hopes and dreams being independent, separate and removed from that of their parents.
To view it as 'just a name' misses a huge amount.