To trademark the names. No other reason as far as I know.
This.
Why changes Joe Hennig to Michael McGillicuty. Mr Perfect was awesome why make his son not use his own last name Is it just incase in the future if we goes somewhere like TNA he an't use the name they have built up/ Same with Husky Harris - come on he could have a better name,
Joe Hennig was changed because it can't be trademarked, that doesn't excuse the last name though, they could've called him Mike Hennig which they'd still have owned. With Husky Harris it's especially stupid. His real name is Windham Rotund
a, in FCW he was called Duke Rotund
o so the name was already gimmicked, there was no need to give him that ridiculous name, especially when they're acknowledging who his father is. My hope is that at some point they'll make it clear that Harris is his first name and make Husky his nickname, as in 'Husky' Harris Rotundo
McGillicutty is his mothers maiden name.
WWE can name people whatever the hell they like.
Technically it's Leonard which is his mother's
real maiden name

Still, that's the keyfabe explaination which oddly enough I posted in the NXT section prior to WWE making the claim. Coincidental I'm sure.