Some people have names that are common enough that it can be challenging to find an available user name based on one’s real name if one does not wish to adopt the rather impersonal-feeling formula of name + string of numbers.
It also means that use of a real name becomes less meaningful as a way of vouching for the authenticity of the data, if it could refer to any of a dozen people with that name.
I have occasionally wished that I had chosen something that projected a bit more professionalism than an inside joke based on a typo for “epiphany” (I don’t know, “blackbees” or something, given my interest in the genus Xylocopa), but I suspect it would cause too much confusion to change it now. I do provide my real name in my profile, which I have mixed feelings about because it is not a common name where I am currently living and thus perhaps makes me a bit more findable than would be desirable.