This debate (and the reasons for/against) seems to me disturbingly similar to the debate between command line vs. GUI in the Linux world. Must just be coincidence...

Whenever I am not using an IDE, I miss it - but mostly for the intellisense. Sure, I can, and have, read through, memorized, and/or printed out the header files or docs of whatever API I'm using at the moment. But why go through the trouble when I don't have to? For myself, whatever quickness I might gain from using a streamlined text editor would never outweigh the time I would loose looking up the parameter order of overloaded method #2 of Class XYXX in Library #514, version 3.3.

Or maybe I've just grown lazy in my older age

Scripting useful tools into vim? You mean, integrating them into vim? Why would anyone want to integrate their development environment?

Some of them probably just want to differentiate their development environment.