We want on-chain fees to be as low as possible for as long as possible, as it helps with the security and scalability of Layer 2s
Similarly, we don't want people to put more monetary transactions on-chain "in order to price out the spam", for the same reason basically. If your monetary transaction is going to increase the size of the UTXO set, we'd prefer you to use a Layer 2, even if that means the blockspace is taken up by an OP_RETURN instead
The only time we want people to put transactions on-chain is if they consume more inputs than the number of outputs created
TL/DR: the long term goal is to keep blockspace cheap, to help with scaling, and for the inevitable spam to be in OP_RETURNs and in Witness data
Similarly, we don't want people to put more monetary transactions on-chain "in order to price out the spam", for the same reason basically. If your monetary transaction is going to increase the size of the UTXO set, we'd prefer you to use a Layer 2, even if that means the blockspace is taken up by an OP_RETURN instead
The only time we want people to put transactions on-chain is if they consume more inputs than the number of outputs created
TL/DR: the long term goal is to keep blockspace cheap, to help with scaling, and for the inevitable spam to be in OP_RETURNs and in Witness data