Great idea. So, how would you access this?

I went through the source code, but couldn't find it?

Would it work on the port exposed by the JSON-RPC interface set in the bitcoin.conf? So for example: localhost:8332/rest/tx/TX-HASH?

Would you have to set tx-index=1 to get transactions with all spent outputs? The same way the getrawtransaction works at the moment?

Great idea. I started building a Bitcoin-Node-API that exposes the commands in a similar way.