How many people still have a corded phone, and how many of those would remember that those phones still work when there's no power?
It's much more important to ensure that the cell network is resilient. Backup power, mobile towers that can be deployed to disaster areas, and continuing the rollout of satellite connectivity will help far more people than maintaining landline infrastructure.
Not in the UK, but almost everyone I know has a landline in their house (although some may be VoIP). In a disaster scenario the cellular networks are going to be overloaded.
My grandparents - and I imagine many people of their generation would assume that if their power failed, they could still pick up the phone and dial someone to get help, as they always could in the past. Not to mention that, at least in the case of my family, they may have a mobile phone but that doesn't necessarily mean they can remember how to use it.