It is very Apple to market a cost cutting move of not including power adapters with their products as an environmental decision. Like it certainly does help the environment, but does anyone actually believe that is the motivating factor?
While I can appreciate the reduction in cost likely was a factor, I wouldn't doubt that the environmental aspect was also a genuine concern.
Their ideal customer is somebody who upgrades devices frequently and then participates in the trade-in programs, but the adapters and such are not part of those trade-ins. So if you get a new phone every year for 4 years, you have 4 adapters. It's not a far stretch to imagine that their own employees said "You know, this feels wasteful" and management said "Hmmm not only is it an environmental problem, but we could also reduce costs."
But it's impossible to say for sure from an outside view.
Reduce, reuse and recycle.
I don't think most people get a new phone every year, hence the "is this worth the upgrade?" Conventionally speaking, most tech reviewers tend to suggest that the latest model usually isn't worth the upgrade if you have the last model, and only in some cases is it a compelling upgrade from two releases ago.
Release a new phone every year isn't the same thing as encouraging everyone to upgrade every year.
I'm a geek and I could afford buying the latest phones, but in practice I almost always get a phone at least 2 generations behind.
That said, looking at people in town, there's a significant number who do get the latest model. I always wonder how they can afford it.
So in some sense, if you replace your phone as soon as a new one is available, you pay about 50% of the new phone's cost every year. So it's not quite as expensive as you'd think. (And yes, iPhones sell for a little over 50% of their purchase price after a year.)
I can't find it these days because their website has gotten more and more full of information, but they used to have a page that specifically said they had a plan to eventually manufacture all iPhones from old iPhone parts.
If you participate in Apple's trade-in programs, consumption isn't an issue. They have a greater capability to successfully recycle the components than anybody else will (e.g., if you send your used phone to some other place to be disassembled).
"If you participate in Apple's trade-in programs, consumption isn't an issue."
If that's how you feel, then Apple's marketing has done its job of removing environmental concerns from your purchasing decision even though there is still a lot of waste in buying a new phone yearly.
Another factor is the EU slowly closing down on their loopholes for nonstandard chargers. They are probably trying to minimize costs in preparation for the eventual reckoning (i.e. which production and packaging chains will have to be modified).