I always found the embedded javascript weird in an ironic sort of way.

There was postscript right, and postscript has a pretty great rendering engine. however the problem is that postscript is too powerful, as a Turing complete language it is hard to use the script results as a document. So adobe used the same rendering engine, tore out the Turing complete bits, added a bunch of structure and ended up with PDF. And the irony... they then proceeded to put the problematic Turing complete bits back in in the form of (spits in disgust) javascript. Hell, if they absolutely needed a scripting language embedded in their document(debatable) they should have put postscript back in.