While I do appreciate a user-replaceable battery, I certainly don't agree that a non-replaceable battery is purely, if even mostly a greed decision.
First and foremost, design challenges. It's much more difficult to design a phone (especially a larger one) that's rigid enough to survive normal use while not being able to count on the back for structural support. Furthermore, you need to dedicate interior space to the closing/locking/waterproofing mechanisms. Same goes for spring-loaded battery contacts and some minor sort of retaining mechanism. The choice of materials for the back is also limited. You effectively can't do a glass-back anymore (which is great for rigidity).
Then, you need to protect the rest of the interior for when the battery is swapped. This takes up further space, and forces certain layout changes.
And finally, you introduce an additional problem - 3rd party batteries. Bad quality, defective, dangerous 3rd party batteries. People want a spare battery so badly...but often are disinterested in paying the ~$50+ for one when there are ones for $10 in amazon/ebay advertizing "exact match, same as OEM" nonsense. While some might tack a greed charge on this, it's actually a revenue option for the manufacturer. They'd sell quite a few batteries too.
And finally, you CAN still replace the battery down the road when it eventually loses capacity. Granted it requires much more work, but absolute worst case I can imagine involves replacing the battery yearly.
So no, Samsung wasn't greedy by making the battery non-replaceable. They were stupid that they rushed a(n otherwise awesome) product to beat Apple to market (there's some greed if anything) which had an inherent design flaw (twice) and resulted in a huge cost to them and inconvenience to consumers.