Actually, with respect to the Perrys, that is not at all the case.
1st, with one or two ASW helicopters embarked, the Perry's are excellent ASW platforms, and that type platform is a very critical component to the ROCN's overall defense and warfighting plan.
2nd, depending on what, if any, upgrades the ROCN ultrimately adds to the Perry's, they could be made to be much more effective in the AAW and ASuW roles. Other nations have done this and the ROCN could do it too. FAter all, at this point, if they add all eoight, the ROCN will have 16 Perrys. Adding a cvapability for an 8-cell Mk-41 with 32 ESSMs addresses the AAW role, adding cannister launched ASMs, even the ROCN's own missiles, addresses the ASuW role.
3rd, as they are, the vessels would be very effective in terms of enforcing the ROC's maritime claims against poachers, piracy, or any 2nd tier naval force.
So, the decision to replace the older Knox class vessels with these Perrys is a good one, and one that increases the capability and deterrence of the ROCN.
I do agree that the ROCN needs several modern D/E AIP subs.