I agree, OP_0,RETURN should be pruned by design. If the data is not written on a spendable output, and saved by the owner, it deserves to be pruned. So is the current 0.5 sats/Byte high enough to allow a person to etch their full-length book into a UTXO? A book is about 1 MegaByte, thus 500,000 sats transaction fee, or $1.00. Consider you can buy a 16 TeraByte HDD for $350, or 2 pennies per GigaByte. So now we're talking about how much electricity cost to keep HDD spinning. You'd have 98 cents left-over to spend on electricity, and while that's happening 500,000 sats might go from $1.00 to $1,000 in value, thus inspiring the owner to spend the UTXO (which would be like pruning it).