I just can't buy this logic. Apple builds these devices at nearly price-is-no-object levels (within reasonable limits). They put in the best screens available, design custom SoC's that are consistently top-tier, use materials in the casing that are much nicer than necessary, and even explore exotics like sapphire and liquid metal. Given all of that I just don't buy that they choose to outfit these devices with less RAM to save a dollar per device (or likely less at the scales they work at). They know something we don't. I suspect it is a combination of power consumption concerns and forcing app developers to keep their code tight. We also have the evidence to prove that even on other mobile operating systems the behavior is largely the same despite more ram. It's just not convincing that this is done for cost reasons.
That said I too wish they would do something about it. It's the most irritating thing about the otherwise fantastic browsing experience on these devices - which are frankly the fastest and smoothest devices I own including my new high end laptop.
"They put in the best screens available"
not really. look at the plus for instance. 1300:1 contrast versus the 1400:1 contrast on the 6, 1920x1080 which isnt even the resolution things are rendered at 2208x1242 so the hardware has to downsample to 1920x1080. Not going to lie and say it's a bad screen but apple did cut corners with it a bit. The regular six has a not so impressive resolution, but its near the point where you cannot discern pixels at average use distance so I won't fault it too much for that.
"design custom SoC's that are consistently top-tier"
Top tier but not perfect, apple has gigantic profit margins if they could shave off 5 dollars from gimping on RAM and still sell as many phones they are going to do it.
"use materials in the casing that are much nicer than necessary"
I can't comment on this with 100 percent accuracy but I've heard that the "aircraft grade aluminum" is bs and all marketing, furthermore the sapphire screens didn't make a show this time around, and the iphone 6 plus has questionable structural integrity. The devices seem quite weak, I suppose the materials are pretty good, but again, their margins are too.
"They know something we don't. I suspect it is a combination of power consumption concerns"
this is false. Someone a smarter than me calculated (i really should have bookmarked I'll see if I can find it) that the battery usage difference if they had added 2gbs to the SoC would be nonexistent. It's a cost thing.
"forcing app developers to keep their code tight. "
I really hate this reasoning, it also hinders app development and progress because it gives them far less to work with.