Absolutely..  if and when I want my notes stored in perpetuity , I will be careful enough to install my own relay .. 

If not , there is no point collecting the garbage .. in fact , everyone must be mandated to remove garbage .. 

A free public relay should store data for say 30 days .. a paid relay for 90 days .. and a personal relay for as long as you want .. 

The 90 days limit even on paid ones ensures that the storage price is lowest possible .. so that people really don't mind shelling out say ten sats per message to keep it around for 90 days ..

It will clean the system up .. makes the the micro- commerce a habit and incentivize people to offer more small paid relays .. and also to self host ..