It sorts like a way to efficiently compress the weight of blocks by removing something that's not needed when possible.
As merely one question, can we really consider the signature as something that's not needed?
I get that we're not _eliminating_ the sig, merely putting it in a separate (segregated) container, apart from the rest of the transaction. But any entity that wants to operate bitcoin in a trustless manner is going to need to be able to fully validate each transaction. Such entities will need the signature, right? Accordingly, such entities will need both components, so no data reduction for them, right?
Currently, relay nodes verify each transaction before forwarding it, do they not? If they are denied the signature, they can no longer perform this verification. This seems to me to be a drastically altered division of responsibilities. Sure, this may still work, but how do we know whether this is a good repartitioning of the problem?
Further, does this open a new attack vector? If 'nodes' are going to stop validating transactions before forwarding them, then there is nothing to stop them from forwarding invalid transactions. What if an attacker were to inject many invalid transactions into the network? Being invalid, they would be essentially free to create in virtually unbounded quantities. If nodes are no longer validating before forwarding, this would result in 'invalid transaction storms', which could consume many times the bandwidth of the relatively small number of actual valid traffic. If indeed this is a valid concern, then this would work exactly contrary to its stated goal of increasing scalability.
Note I am not making any claims here, but I am asking questions, prompted from my incomplete understanding of this feature.