I don't think I've ever heard of a recent adopter who's changed a name just for the hell of it. I'm not going to say it's never happened but it would be so rare that I don't think you can extrapolate that into all name changing is bad.
Re. success being based on talents not names, that's true, but it's not the whole truth, and I think you know that. Think about all the situations where someone knows your name before they know anything else about you, everyone makes snap judgements based on your name; why do you think the 'Baby Names' board on here is so busy?!
There have been lots of studies done about BME applicants using 'white' names and having more success getting job interviews. I'd bet money on the same being applicable for the kinds of names we're talking about. Add onto that all the standard identity issues that adoptees often face (irrespective of names), and a name that marks you out as different, doesn't fit with your family's names, your friend's names, your colleague's names etc, a name that gets commented on, that puts you at risk of being traced by people you may/may not want contact with and you've got an awful lot of problems to deal with. All of which could have been prevented very easily.
I'd risk psychological issues over being hunted down, attacked, living in fear etc any day. You're living in cloud cuckoo land if you seriously think children should be brought up looking over their shoulders just to avoid the potential for identity issues over their name. You need to ask adoptees who were raised with the risk of being traced by abusive birth families etc whether they'd rather their names had been changed (changed doesn't mean completely changed, it often means correcting a spelling, or using a very similar name such as the Chardonnay/Charlotte example) and they'd have been able to have a 'normal' childhood.
I don't think anyone has said that not having to change names isn't the ideal scenario, but I think you're imagining a very black and white world where a set of rules could be laid down for when names can/can not be changed. Almost everything to do with adoption is a sliding scale of shades of grey.
Re our situation, I don't for a minute think it happens every time names are discussed (I've got DC upstairs as proof), but I don't think it's rare either. Since you don't want to say what your connection to adoption is, you may or may not be aware that the SWs hold all the cards; you either toe the line or you won't be matched. It's often the case that the only people fighting for the children are the adopters. SWs can get too wrapped up in out of date theory and getting their own way that they lose sight of real life. It was our experience that very, very few of them had even contemplated the impact the internet would have on the security of placements. We used to have a book about it, which we gave to our SW for future use because it explains exactly how dangerous the internet can be for an adopted child. The last I was aware it was recommended reading for SWs and adopters..... and it recommends name changing where there is a risk.
@comehomemax hello! I haven't got the foggiest who you used to be! 
@Italiangreyhound thank you for the flowers. I don't think we'll ever not wonder what happened to them and hope that they're happy, healthy and loved.