Around here, it seems like there's somewhat of a consensus that generalist programming languages (that try to be good at everything, support multiple paradigms, support both very high- and very low-level programming), etc. are a bad idea, and that it's better to pick the right tool for the job and use lots of different languages. I see three major areas where this is flawed:

1. Interfacing multiple languages is always at least a source of friction and is sometimes practically impossible. How severe a problem this is depends on how fine-grained the interfacing is. Near the boundary between the two languages, though, you're basically limited to the intersection of their features, and you have to care about things like binary interfaces that you usually wouldn't. Passing complex data structures (i.e. not just primitives and arrays of primitives) between languages is almost always a hassle. Furthermore, shifting between different syntaxes, different conventions, etc. can be confusing and annoying, though this is a fairly minor complaint.

2. Requirements are never set in stone. I hate picking a language thinking it's the right tool for the job, then realizing that, when some new requirement surfaces, it's actually a terrible choice for that requirement. This has happened to me several times before, usually when working with languages that are very slow, very domain specific and/or has very poor concurrency/parallelism support.

3. When you program in a language for a while, you start to build up a personal toolbox of small utility functions/classes/programs. The value of these goes drastically down if you're forced to use a different language than the one you've accumulated all this code in.

What am I missing here? Why shouldn't more focus be placed on generalist languages? Are generalist languages as a category dying or alive and well?