[jakobegger]

I'm pretty sure that rootless is a good thing. I've seen Macs bricked by seemingly harmless operations like changing important permission settings, or by damaged installer packages.

Locking the system down will make it a bit harder to shoot yourself in the foot. Besides the obvious advantage of reducing the attack surface of vulnerabilities.

[super_mario]

That won't brick your OS X installation. Just boot from external drive and fix the permissions. It's not really that hard, and there is even a recovery partition exactly for problems like that.

[jakobegger]

Yep, the recovery partition is also a pretty great feature. But it's even better if you never need it!