Fancy IDEs are lubricants for high-friction languages. If a language is already low-friction, there won't be much benefit to be gained from an IDE, as even a plain text editor will already get you near to optimal productivity in said language.
Personally, I'd rather use a plain-old "code editor" (with at most syntax highlighting, but no snippets, let alone autocomplete), in part because doing so will actively steer me away from languages that weren't designed with the User Experience of writing them in mind.
Imagine if there was a hammer that was so badly-balanced that—despite being not too hard to lift—you needed to be wearing a powered exoskeleton to accurately hold and swing it. That'd be a bad hammer, right? Hammers are hand-tools; it's an expectation that they'll work when used "manually", i.e. with raw human capability alone.
Programming languages are hand-tools as well, in an essential sense. Like mathematics, the "interface" through which we manipulate a codebase is plain, raw text — sequences of symbols. We humans understand source code by reading it with our eyes; and then we write or modify it by editing it the same as any other text. We can do the whole thing on paper, or a blackboard, or even purely in our mind's eye. That's kind of the idea behind having a source code representation of a program in the first place, divorced from a machine code representation — to give us humans a formalism we can intuitively handle. A programming language is something you can think in.
Seen through that lens, a programming language that requires the cybernetic prosthesis of an IDE to read and write it fluidly, is a bad programming language. You don't have an IDE loaded in your head. So how will you think in it? (Usually: by thinking in a vague pseudocode instead; or even, by thinking in a different language than the one you're writing in. Obviously, this is going to be lower-productivity than coming up with a mental model of the problem that can be directly typed into a computer.)
(Before anyone makes a supposition about my language biases: both "complex" and "simple" language designs can be inherently high-friction due to their design choices. Scheme has very little syntax, but it's also high-friction, in that it's easy to get lost in a sea of parens unless your editor helps you along with a feature like Emacs' paren minor-mode. Most modern code editors do have something like that, but it's still a form of lubrication to overcome a point of friction in the syntax; one that some of Scheme's linguistic siblings—e.g. Clojure—avoid by increasing syntax.)