I actually just noticed this the other day because I haven't been on in forever. (Mostly due to being busy and my laptop doesn't work like it used to.) Anyways I logged in as a guest and noticed my name was Tomato Garden. Yep Tomato Garden.
http://prnt.sc/a4omn2 So far I like it. You can tell players apart easier. And being word names instead of just numbers they may be taken for registered accounts. Which should in theory cut down on all the guest hate since it will be slightly more difficult to tell the registered from the nonregistered.
However I can't really seeing this change make guests want to register anymore than before. But then I don't see the sense of not making an account to begin with. I can understand if you first cross this game and do a trial run in Guest mode before taking time to make the account. But why hold off any longer? You can still practice in Guest mode even if you have an account.