store of value comes first in any currency, especially when it is rather scarce, after it becomes a widespread savings instrument it can then become a payment instrument (medium of exchange)

yes, most relays delete them, not all clients expose the capability... https://next.nostrudel.ninja and https://coracle.social both have interface components to do this (on coracle it's in the ... menu on the bottom right of the note's panel) 

 Amethyst has the feature to do so, if you are using Android, Amethyst is probably your best option. Beware, some relays will not delete it, assume all you write in Nostr is forever .

Bitcoin for payment.. Well, the Satoshi dream of p2p cash , IMO, was death from the start due to a simple feature missing: PRIVACY. That, from the beginning made it quite a challenge, paying to someone would give away your wallet's worth... We have been progressing slowly but surely in the right direction, LN is an improvement, cashu mints are a layer of good privacy for small payments (not ideal, custodial mints), Ark will be excellent if that protocol ever see the light...But for the users with no technical background, not ideal, easier to pay with cash or other methods that are more private online. 

Unfortunately most software is built without thinking on privacy and transacting with no privacy is utterly dangerous.