It might not hurt, but the applications and the systems must IMHO be designed to deal with the situation that when they (re)start, the address might be different. I.e., the lifetime of the address does not *necessarily* have to be longer than the lifetime of the application process.
The "application" may be more complex than just one process. Stable addresses across reboot may be necessary. I want to be able to build apps that take advantage of the large IPv6 address space and consider that addresses are stable.
On the other hand, as long as John Doe's home PC stays powered on and connected to the Internet, his address should stay stable.