The ecosystem makes it feasible to use the language or not. For my personal projects, I won't use a language that doesn't provide some kind of straightforward

The ecosystem makes it feasible to use the language or not. For my personal projects, I won't use a language that doesn't provide some kind of straightforward cross-platform GUI toolkit (nearly) out of the box—which narrows the field enormously. But it's the syntax and semantics what determine whether I'd want to use the language to begin with, and how maintainable the resulting code is.