Spillman doesn't suffer from the liveness requirement and therefore the attack surface of lightning. No toxic data to protect.
Also, the LN protocol implementors made a (IMO grave) mistake replicated in many places by most btc protocol devs of ignoring mining. In lightning's case even overloading miners with an additional and uncomplementary role: low value HTLCs are escrowed by miners. This opens a fundamental protocol vulnerability where bitcoin block producers who run a LN node can jam a channel with low value HTLCs, take their node offline, and mine the force close tx themselves, stealing from their channel counterparties.
If we're serious about decentralizing mining as a community we need to think long and hard about a world where anyone can mine a tx permissionlessly. I think lightning in it's current form is not suited to task for mining pool payouts.
Real talk: ecash is the perfect tool for low value fees. I think it has a place in LN and BTC protocols. I intend to pursue on-chain ecash tx fees. Not sure if it's worth it to pursue fixing LN fees. I think it's probably way easier to just use other L2 protocols that are less broken and less entrenched. But we'll see. I'm always open to change my mind in light of new evidence.
In any case, if we are successful in decentralizing mining the LN protocol will have to adapt to the new reality. I don't see any other way forward for bitcoin.