I think, in many peoples minds, extensibility == pain; either lots of code configuration (hello java, ejb), or xml (hello hadoop, java, spring, ejb), or tons of code (hello java, c++), etc. When nice languages don't make things painful, it sometimes feels like it's wrong, or not really enough work, or in some other way, insufficient. But people can mistake the rituals of programming for getting actual work accomplished.
Simple: because std utils are programs that do what they supposed to do. if problems bound are well within the definition domain of a std util then its all good. Supportability and Extensibility is way too generic for you to draw a line saying std utils can handle them all. After all, they are programs, not programming languages.
