It's been implemented, you can setup these kinds of escrows just using bitcoin core and have been able to for years. It's just another application of multisignature, which is what P2SH was created to make it easy to pay into without special software support.
There have been commercial services based on making these kinds of transactions-- e.g. Bitrated.
The reality is that the demand for it in practice is pretty negligible. The issue is that if people think the transaction is at risk they just don't trade. If they think it is not at risk then they don't bother taking actions to secure it.
It's not supremely user friendly to do these kind of multiparty transactions in bitcoin core but that itself is just a product of demand.
As far as Wright goes, he mostly speaks in vague truisms specifically to avoid getting caught out. So for example Satoshi says that he didn't have time to implement it-- Wright says in there since day 1. But if you try to nail wright to a cross on this he'll just say that he meant the potential was in there as part of the design.
As someone who has handled 20,000 BTC in escrowed transactions over a period of nearly 15 years I can tell you that Bitcoin's implementation of escrow was dead on arrival. The idea that people won't act irrationally while funds are held in escrow is ridiculous. The amount of trades I've had to manually intervene to settle differences would have cost users on this site hundreds of thousands if not millions of dollars in losses would have been enough to shake confidence in Bitcoin. Bitcoin does a lot of things well. Escrow is not one of them. I would even say that attacks against escrow agents on this site to spread distrust and enable scammers are partially to blame for the extreme loss of economic activity on this forum.