Yes, I would push them for a new unit. That's ridiculous to have a receiver die after only a year. I would push them for good customer service (replacement) seeing they need something to offset the poor quality of their product.
If the speakers do present a hard load to drive, the receiver's protective circuits should had kicked in, shutting the amp circuit off before damage occurred. The receiver would had been very hot to the touch as well, right before protective circuits kicked in.
Most manufacturers replace defective units if they fail a short time after purchase or if the model is no longer available for some reason, they don't replace anything after a year, especially if the cause of the failure is unknown and at this point, it's unknown.
It's also not fair to them to go online and say that their product is of poor quality and they're providing bad customer service. I'm not defending Onkyo, per se, but I disagree with thinking that they owe a replacement, based on a failure. I do have a problem with the AVR being returned with the trigger not working, though. However, it' not the first time I have seen something coming back from an authorized or even a company service center that had a problem.
I think this situation is mainly caused by the manufacturers ending their support for local service shops, but A) it's financially unsustainable and B) the loss of retail stores and service departments was largely caused by the loss of support for local B&M, first going to the big box stores and when they failed (Circuit City, etc), shoppers went online. Sure, the cost is lower, but people are often dissatisfied by their purchase and need to chase their tails in order to find what they think they want.
Onkyo, Pioneer, D&M, McIntosh, Harman International and other brands have been sold at least two times- that's not going to stop and we will see an end to many of these. Some brand names have been resurrected, but they're nothing like what the companies were i n their heyday. With low prices, comes less of something.
There's a saying in construction- "You can have it good, cheap and fast- pick two, because you can't have all three".