Good points, and I agree that it's a continuum. Ease of development comes at a cost - the cuteness of Ruby is great for enumerables and lambdas, but also allows you to shoot yourself in the foot.

Personally, I don't think type specifications are incredibly onerous, and I'd rather err on the side of a compiler catching my dumb typo instantly, instead of waiting for a 15-minute CircleCI run to finish.