That's quite the non sequitur - the increase in driver complexity was most likely due to the nature of the device becoming more complex, not just the plug and play. Unless you can demonstrate that the problems you encountered were due to the PnP portions of the driver, you don't really have a case. You might as well blame it on aliens. My personal experiences are very different to yours - fiddling around with jumpers was far from ideal, and as soon as PnP hit the scene and was properly supported by enough drivers, it was a great improvement on what came before.
If you couldn't configure your internal modem, the problem lies either with you, your computer, or the modem - blaming a technology which was used to great effect by countless millions of people doesn't seem the particularly rational approach.