The only way what you write makes sense is if Apple were dumping, not Google or Amazon.
Dumping to protect market share, then jacking prices back up once the competition has been seen off.
But with new entrants trying to compete with an incumbent with an enormous lead, I don't see anything wrong with making the investment to sell at cost or a loss. The consumer wins because they get hardware cheaper and more competition which should drive prices down across the board. The only people losing out are the people previously in a monopoly-like situation.
Do consumers really win here? If your only indicator is that they save a couple of bucks, then sure. But there is more behind consumers winning.
Imagine a scenario where a company is able to cut costs, never over take the market leader and eventually dump the product, support and all (because they can't afford it due to the low cost). Does the consumer, who is still tied to this device, still considered a winner? The argument can be made that the company can then raise the price to try and offset the low cost previously. Sure, they can do that...and if they get caught, they could be called out for predatory pricing.
There are so many ways to compete with an incumbant, and price could be one of them. The only pitfall is the scenario (which has happened time and time again) of hemorrhaging losses because you are solely competing on price.
Competing solely on cost relies on heavy volume being sold in order for it to even provide razor thin margins. The companies will continually lose here because they aren't able to really recoup their investment put into the device.
In my opinion, the consumer only wins when the company wins because of the intangible benefits a company can afford to provide such as support and customer service. Without these, I don't see the consumer winning with companies competing solely based on price. And I think Apple is the perfect example for this (only because I cant think of others). They charge higher than normal for their devices, but they have great support and are willing to bend over backwards to make sure you as a customer are happy.
What you say is true when there are only two competitors - every move by the underdog will then be good for consumers. But chances are that a dumped Nexus/Kindle will hurt others much more so than Apple. (Most likely example: Google may push Amazon out of the tablet market, which would be a loss for consumers.)
Dumping to protect market share, then jacking prices back up once the competition has been seen off.
But with new entrants trying to compete with an incumbent with an enormous lead, I don't see anything wrong with making the investment to sell at cost or a loss. The consumer wins because they get hardware cheaper and more competition which should drive prices down across the board. The only people losing out are the people previously in a monopoly-like situation.