You can't compare used prices against new retail. That's not fair. If you did, I can pick up a mint S6 Edge for €380 here compared to €749 for the S7 Edge and the user experience is much the same ...
It's also a little ironic of folks to say that Samsung deserve kudos for listening to ITS audience and giving them the device they wanted.
I am quite sure that many iOS users wanted the iPhone 6/6S updated hardware and memory in the 4" form factor and were peeved when there wasn't that option. Heck the forum was alive with frustrated users after Apple increased its sizes. So essentially they have now listened and given that audience what they want. 6S speed and internals in their preference, a 4" size / frame.
I do not understand the mentality on this forum that folks seem to think every device any company launched is FOR THEM. As if its merits are only valid if it appeals to them. It's much the same as the 'entitlement' generation. Whether you or I like a device or not, whether we're the target audience or not, it doesn't negate the fact for many people it may be exactly what they are looking for and at $399/499 it provides them the most affordable entry into Apple's smartphone lineup. Whether you think it's value is justified, does not mean it's not worth it for others.
People here always say they love technology, and yet seem to think of every device released isn't for them or exactly as they want it - then it's rubbish. That's not loving technology, that's the opposite of loving, it's just ignorance and arrogance. And it's very common on these forums .