Skuzzy,
You're right of course... *however*, it still seems that even with the additional connectors, the power is still "good enough" and well within the capabilities of the computer hardware to deal with...
If you haven't seen HardOCP's PSU reviews, you really need to do so. They have some gucci test equipment and what appears to be a good testing methodology. They test not just voltage, but noise and ripple, under conditions we might actually see in use such as varying loads and with varying non-optimum input voltage.
As for degrading over time, you are completely right that using good (ie. expensive) connectors is the only way to deal with that. But that's no different from (for example) SATA cables or even fan power connectors crusting up over time and causing problems.
Jerry Pournelle swears by a connector cleaner called stabilant... Back when men were men and connectors were always flaky, he reported a degree of troubleshooting success by unplugging connectors, brushing on some stabilant to clean the connectors, and plugging them back together. He "saved" a lot of hardware that might otherwise have been condemned as broken by just ensuring the connectors were good.