Possibly no need to learn anything new. Since GPLs are used in many domains, there’s a chance you might not have to learn a new language at all. This is especially true of Pulumi, as it supports several of the most popular languages in the world, including JavaScript, Python, and Java. If you already know Java, you’ll be able to jump into Pulumi faster than if you had to learn HCL to use Terraform.

Bigger ecosystem and more mature tooling. Since GPLs are used in many domains, they have far bigger communities and much more mature tooling than a typical DSL. The number and quality of Integrated Development Environments (IDEs), libraries, patterns, testing tools, and so on for Java vastly exceeds what’s available for Terraform.

More power. GPLs, by design, can be used to do almost any programming task, so they offer much more power and functionality than DSLs. Certain tasks, such as control logic (loops and conditionals), automated testing, code reuse, abstraction, and integration with other tools, are far easier with Java than with Terraform. 

Easier to learn. Since DSLs, by design, deal with just one domain, they tend to be smaller and simpler languages than GPLs and therefore are easier to learn than GPLs. Most developers will be able to learn Terraform faster than, say, Java.

Clearer and more concise. Since DSLs are designed for one specific purpose, with all the keywords in the language built to do that one thing, code written in DSLs tends to be easier to understand and more concise than code written to do the exact same thing but written in a GPL. The code to deploy a single server in AWS is usually going to be shorter and easier to understand in Terraform than in Java.

More uniform. Most DSLs are limited in what they allow you to do. This has some drawbacks, as I’ll mention shortly, but one of the advantages is that code written in DSLs typically uses a uniform, predictable structure, so it’s easier to navigate and understand than code written in GPLs, where every developer might solve the same problem in a completely different way. There’s really only one way to deploy a server in AWS using Terraform; there are hundreds of ways to do the same thing with Java.