I suppose it depends which way you look at it. Lots of people are buying books that they probably wouldn't have paid for if the prices had been much higher. You have to hope that that is offsetting the sales that they're losing from people who were planning to buy them anyway but would have paid more for them.
It is surprising that some of the offers are for relatively recent books, though. You would have thought the price cuts would maybe kick in after a certain period of time, and wouldn't be so steep.
For example, the second volume of The Vision only came out six months ago, and it's £1.80. For a six-issue trade (and the first volume is the same, so you can get the entire series for £3.60). That's 30p an issue, cheaper than even the most generous Comixology sales, and for a book that's been pretty high-profile and well-reviewed.
I think there's probably a balance to be struck somewhere in the middle. There is a risk with these Amazon prices that the product itself is devalued in the eyes of customers. Will anyone pay full-price for digital comics when offers like this are being made?
(I guess the answer is yes - I still buy some issues full-price on day of release, and pay more for a single one than I'm paying for some of these collections - but it's creating a much broader spectrum of pricing than we've been used to even from the Comixology sales.)