My personal guesses why Ada lost: In (Western) academia was a massive dislike of Ada because of its DoD roots and NATO applications, so they didn't use it for teaching. And hackers disliked it because it was a committee-designed language and it's pretty restrictive (even paternalistic) and directed toward mediocre programmers (a good decision for systems that run over decades and have big, changing teams assigned to it).
What was meant half-joking (that they should use Ada for the browser) becomes better the more I think about it. When I look at Rust's design goals, I find that Ada 2012 fulfills them (at least superficially). Additionally: if users have to learn Rust as a new language, then they can use Ada anyway (which has a good track record, while there's no experience with Rust's possible quirks).
And I guess if they ask AdaCore to include certain features as add-ons to their GNAT compiler, they'd do it or assist (because for fun and for the publicity that Firefox uses Ada).
In Europe maybe. In the US, hardly. We're talking early nineties, not the sixties. In the IT academia there were hardly any leftists that would oppose a language on the basis of it being used by the DoD.
I don't know why people think Ada is restrictive, it really isn't at all, at least, not since the Ada 95 revision (which added pointer-to-stack and pointer-to-function and OOP). It isn't even verbose, it's just communicative.
I think it comes from the following: Ada was designed to be robust against the average programmer. They prefer to "hack" around and have their program just compiling. Compared to, say, scripting languages Ada ist restrictive. I feel they dislike Haskell for the same reasons.
edit: most complains seem to come from strong typing and static type checking.
What was meant half-joking (that they should use Ada for the browser) becomes better the more I think about it. When I look at Rust's design goals, I find that Ada 2012 fulfills them (at least superficially). Additionally: if users have to learn Rust as a new language, then they can use Ada anyway (which has a good track record, while there's no experience with Rust's possible quirks). And I guess if they ask AdaCore to include certain features as add-ons to their GNAT compiler, they'd do it or assist (because for fun and for the publicity that Firefox uses Ada).