Eventual security, perhaps, but that's a loooong stretch-goal. The fact of the matter is, even Servo, which is written-from-scratch and lacks all the UI goodies, is only a fraction Rust. It'll be a long time before supported libraries could be rewritten and rust, and I reckon a rewrite of all these things is likely to cause more new human-error security flaws than it will eliminate pointer/memory related security issues. In the (very) long run, though, I agree.