When a person takes on a new name, it’s often an act of discarding an old identity so they can take on a new one. This can typically be for either the good or the bad, but it’s most often for the bad. Discarding a name usually means getting rid of all ties to that life, including family and friends, so that the person can pursue their own ambitions. Renames almost always have some sort of symbolic meaning behind them, and the characters don’t typically shy away from giving you that reasoning.
Why this can be bad: It’s really easy to fall into the corny trap. I’ll admit it: I love Harry Potter, but when I found out that “I am Lord Voldemort” was an anagram for Tom Marvolo Riddle, I thought it was kind of lame. It grew on me, obviously, and it could have been a lot worse, but it didn’t really seem appropriate to me that he’d take the time to figure out how to make his name into “I am Lord” plus something pronounceable, but I suppose it’s better than him renaming himself to something like “Spike“. Even when it comes to names like that, even if you as a reader completely understand where the character is coming from and will accept the name, there’s always going to be part of you that thinks it’s a little bit lame.
How you can fix it: There’s actually not much you can do, especially if you want there to be some great symbolic significance. Of course, a character going from the name “Galinda” to “Glinda” isn’t really going to ruffle anyone’s feathers, but “William” to “Spike” might. This is something you’re just going to have to accept if you use this trope. And since there are going to be those people who don’t like it or think it’s silly, be sure that you’re using the name change for a clear reason. In my novel Death Defiant, the leaders of the Underworld discard the names they’re born with and take the names of old demons, and those who hope their children will rise to leadership positions might name their children after those demons, as well. Do I recognize that it’s kind of lame to have a guy named “Lucifer” just running around? Yeah. But it’s significant to the demonic culture I’ve built for the world, and I’m willing to accept it.
Bottom Line: Some people might think the name change is corny or silly, but if it’s something you have to do, just accept that not everyone’s going to like it. As long as it’s not too silly, your readers will come to accept it, too.