Here's your good reason: putting random shit into the root of a hierarchy subverts the entire reason a hierarchy exists in the first place.
I would change that... to
"putting random shit into the root if you're rich and can afford to buy your own TLD"
There is nothing subversive within the new gTLDs unless you're up to pay for it.
Soon we'll just have no consistency in domain names.
This would leave the rest of the root namespace available for completely different approaches to resolving names. Think decentralized schemes like namecoin, .onion, etc.
I realize it is too late for that, but this is the way we should be thinking about name resolution, imho.
I bought shall.work for 2 usd, although I admit I only bought it to use the mail it©shall,work for testing purposes.