It makes a big difference in use cases. We will never attend key signing parties. We don't upload our keys to key servers. The web of trust as envisioned by the PGP developers doesn't work here. Because, as I stated, the vast majority of PGP programs don't use it. Blame their developers. The MDC integrity feature is already disabled on their end, my option just turns off the warning, so it doesn't annoy you every time you see it, which would be every time you decrypt a message.