This is why I keep saying that "smart contracts" should be expressed in some declarative notation like decision tables. Byte-coded programs as contracts were a really bad idea. Contracts need to be readable, not just executable.
IIRC, the old Camllight VM was pretty similar (I might misremember, that was literally decades ago); an ML-like language to Michelson compiler is fairly straightforward to write and to prove sound.
I'm happy that they do things the sane way, i.e. focusing on sound foundations rather than on how Javascripty the syntax looks; but I'm afraid the communication isn't as clear as it could/should be. Blessing a compiler for some subset of ML, as a first high level language, would have cleared things up IMO.
The underlying DAG idea has potential. You could have two half-transactions happening on separate subtrees, where A is buying X from B and B is paying Y to A. So A broadcasts "A will buy X from B when B pays Y to A", and B broadcasts "B will pay Y to A when A buys X from B". When the matching half-transactions acquire a common child, the transaction commits. It's a true "meeting of the minds".
You can for example trade user-defined (possible private) assets (tokens) in that way - "Ill send you my bytes for your blackbytes, I send bytes to this address and me can sweep them back after 4 hours, or you can sweep them if payment of X amount of blackbytes is made to my address". It has oracles as well.