Has the cost of building software dropped 90%?

This is a bit like saying RoR or Django dropped the cost of building web apps by 90% because you could write a blog app with 5 lines of code (IIRC early Rails claim).

So yes, the cost of certain tasks may drop by 90% (though I think that's a high number still), certainly the cost of developing software overall has not dropped by 90%.

I might be able to whip up a script in 30 seconds instead of 30 minutes, but I still have to think of whether I need the script, what exactly it should do, what am I trying to build and how and why, how does it fit with all the requirements, etc. That part isn't being reduced by 90%.