It was never a security feature. It's an anti-fraud measure.
It only comes up when you dispute a charge, otherwise there's generally no reason to inspect the signatures.
There is value to always signing in a consistent and identifiable way, because then if you dispute a charge and the signature is substantially different from how you normally sign, that supports your dispute claim.
It's actually a good idea to do something more distinctive than just your name in cursive, as that's likely what someone using your card for fraud would sign with.