I don't want to fix the world (new .def interface, new graphicx, etc.).
With that prerequisite, we'll be waiting forever.  I just want to load
epstopdf.sty by default (when it's useful).  In practice, that is the
99% case.

It seems like we can add the require to pdftex.def or to graphics.cfg.
Heiko, Martin, wdyt?
(Obviously either is far better to mucking about with graphics/x itself,
thanks to all for setting me straight.)

(I did not realize that TL's graphics.cfg was so complex, never having
had occasion to look at it before.  Pretty depressing.)