Doing so is usually pointless. Either your ISP isn't evil, in which case there's no need since you could just use theirs, or your ISP is evil, in which case they'll hijack all of the recursive queries that your own resolver would need to make.
If you have a suitable machine to do so, then couldn't you just tunnel your DNS traffic through it and out its default resolver, without having to run your own?
The question would be why bother with 3rd-party resolvers in that case?
NB I have a slightly different setup - I run Unbound locally and route DNS requests through the 'suitable machine' on VPS over VPN established by my LAN router. I considered moving the resolver there but didn't yet found the setup what would be usable for me when I would be out of my LAN. Opening my resolver to the whole world is the way to be a part of the bot relays for DDoS attacks, so this is out of question.
Root servers only control the mapping up to the TLD. That is, they for instance know the nameservers for ".br", but they know nothing about the nameservers for ".com.br", or about the domains below that. If your domain is "example.com.br", the nameservers which could "just take it down" are the nameservers for ".com.br", not the root nameservers. In the same way, the root servers are completely unrelated to domain registrations (other than pointing to nameservers which know about them).