This gets asked a lot, yet there's always conflicting answers and misinformation posted. So, let me try and clear it up for you going by tried and true experience.
CCleaner is about the only trusted, safe cleaner out there. By default, it doesn't dig deep enough to do any damage. It is safe to use. However, given your question, I liken it to BIOS-flashing. You don't do it just to do it. You do it to solve an issue. CCleaner has helped me MANY times over solve issues, but I don't run it on my systems just because I feel like it. If you need to use a reg cleaner, that's the one to use. If your system is working perfectly fine right now, then there's no reason to run one. CCleaner has other useful parts as well, so it always gets installed for me. But the reg cleaner is there to help me solve issues, or clean up after app uninstalls. it is not part of my regular, routine maintenance.