The goal of brainfuck is to be as minimal as possible. Being bad is just a side effect of that.

If you want a language that was designed to be bad look at Malbolge or INTERCAL.

After looking at those I take back anything bad I ever said about Brainfuck (and also C++).

No, youre right - brainfuck is a good language.

I would call Brainfuck (and other esoteric languages) as an instance of what "critical design" as described by Anthony Dunn. The goals of critical design are to produce artifacts that get you to think vs. "affirmative design" which is meant to create usable artifacts.