I really really think that when adopted children have been saddled with a truly unfortunate name, social workers should discuss with the parents the possibility of conducting a stealthy/gradual name change.
And they do, but generally on the grounds of the child being very identifiable online, and their birth name constituting a potential security or privacy risk, rather than on the subjective grounds of a birth name being displeasing. (Or in one case I know of, because the adoptive parents already had an older child with the same name.)
I think kids' needs and futures need to come first, not the whims of someone who (in most cases) had to have their child removed from them by social services.
Yes, obviously, but adoptive parents and social workers are thinking of the child, and potential future identity issues bound up in early trauma, loss of birth family, lack of knowledge of early life etc. And of course most adoptions in the UK are not small babies, and many children at the point of adoption are old enough to answer to/recognise their birth names.
Whatever social workers' advice/regulations are (and they have defaulted in general to advising retaining the child's birth name when there is no perceived risk), once the parents have the adoption order they are under no legal obligation to carry out that advice.