Murphyman,
I think that you are over generalizing here, Even though many lower end receivers state that they are capable of driving 4 ohm loads the power supplies in them are just not up it. With many such amplifiers, you can drive a 4-ohm load safely, as long as you don't try to drive it too hard. If you drive a low-Z load to too high a volume, one of several things may happen: the amp may begin to "clip" (sounds very harsh and distorted, may damage the tweeters), or may overheat and shut itself down, or in the case of units without a protection circuit built in may overheat and burn up.
In your saying buy more power, you are overlooking the main problem that resides in the flaw of the receiver. I would challenge you to find anyone with the likes of the Denon 3802 the Yamaha RXV1000, or the one of the better Onkyo amps that has this problem. In your buying more power you have also bought yourself a much better power supply that can handle the 4 ohms at higher current levels. You DO NOT need all that power to make these speakers work. You do need a unit that can provide the current, I don’t care if the amp is 600 watts if the transformer cannot deliver the required current for a 4 ohm load you will have problems. A 50watt high current amplifier will do just as good a job driving these speakers as any. The bottom line it was the receiver not the speakers that were your problem.