Postgres is a fantastic database.
That said, I've also used Oracle quite extensively in the past when clients have needed it and it has some features that would be great to have in Postgres - as well as some features which we won't see in Postgres as they don't match the Postgres philosophy. Lack of one or more of the features below have driven the choice for various clients to use Oracle despite the cost, so having them would help grow the Postgres ecosystem.
Features in Oracle I'd like to see in Postgres :
1) Flashback. This name encompasses lots of ways to see data as it existed at a previous point in time.
If you drop a table, make a big (wrong) change etc, being able to flashback to just before it is brilliant. Or if you have a multi-terabyte sized performance test database, running a test and then a flashback to before the test is much quicker than restoring from a backup.
2) More robust partitioning - Postgres is quite lacking in comparison here.
3) Better backup options. PG really needs an in core incremental backup to start with, with something like Oracles block change tracking for backups thrown in to do quick incremental backups of a large database.
4) Replication - the lack of something like Oracles switchover which is used in a lot of architectures where you have a application and DB replicated across two sites, with one site being the active one at a point in time. When you need to take one site down for whatever reason, in Oracle you can just do a planned "switchover" to the replica DB and then switch back whenever you want without having to do anything as the DB knows it was a clean switch.
5) The diagnostic and performance monitoring built into Oracle are more extensive than those in Postgres.
The one other really useful feature Oracle has which will likely never be in Postgres is RAC (Real Application Clusters) which lets you create a multi-node active-active DB cluster quite easily.