

It was my understanding that the closed source part was limited to their visual aspects, as the functional changes they make have to adhere to the licence of chromium. Unless that’s changed; I haven’t looked into it in a couple of years. It’s where their “skin” applies that they keep it proprietary in other words.

It’s an entry into the business.
To get into the union, you have to meet certain minimum work durations. To get those, you often have to build up contacts and a history as a reliable extra. So a one day shoot as a corpse can lead to the three day shoot as a background performer. Or, in some cases, it may be enough to give you the three days.
Since the usual procedurals (csi, l&o, what have you) are shooting scenes with corpses pretty much every episode (with svu being less frequent), it’s a solid chance to get an in.