PQ-secure client-side proving is one of the best defenses against quantum computers and AI-assisted elliptic curve breaks. Say in some near future we find out that AI figured out how to reduce security of elliptic curves. What we thought has 128 bits of security actually has only 80 bits. Everyone needs to scramble to increase key sizes, which means major upgrades to protocols, apps. HW wallets and HSMs may no longer work and we'd need to build new ones, and much much more. Same happens if a viable quantum computer appears. It may not be able to break things fast enough initially - so, we'll have time to migrate - but any protocol where signatures/public key are know to the network needs to scramble to upgrade and change its very fundamentals. But - if we have client side proving, there is absolutely no rush and nothing needs to change immediately. The keys and signatures are never shared with the network, so we can keep using the same cryptography, same HW wallets, same HSMs etc. It would still be a good idea to migrate - but the migration could take many years, and be done much more safely.