There is no solution to spam other than small blocks and fee market - small blocks and fee market are hinting at higher cost to the spammers, and we'll everyone, forcing encoding in pubkey forces just that, the difference is that it punishes only spammers, not valid txs. Spammers right now have a discount, so in a fee market they still pay with a discount VS normal txs. So when ppl say fees are for spam, well, they have a discount, and forcing to use pubkeys increases their costs.