I didn't say Gosu was proprietary. They've taken this whole "open-source" catchphrase and made some CIO's, that generally don't know anything other than budgets and bodies, feel better.
It does, however, tie you completely to the Guidewire platform/products. A very smart move by the company. It will be decades before these slow-moving behemoths will rip out this language that was a blip on the radar. That doesn't mean it was needed or is as historically important as the devs seem to think.
Another in the long line of languages that are created to solve a problem that doesn't exist. Even worse, created as a way to force P&C carriers to be tightly coupled to a proprietary piece of software. With one industry being the only relevance for the language and that industry with usually the worst IT technical talent available.
I get it, Guidewire has some very talented engineers. Probably at least a few of the best in the valley. However, you're pushing it out to the dregs of the IT world and hoping to make it fly and gain adoption when those using it are generally just drawing a paycheck for the pulse their body maintains.
It does, however, tie you completely to the Guidewire platform/products. A very smart move by the company. It will be decades before these slow-moving behemoths will rip out this language that was a blip on the radar. That doesn't mean it was needed or is as historically important as the devs seem to think.