I think you have to look at the actual market: Linux is primarily used by people who are power users; I'd go so far as to say that the vast majority of people using Linux are power users, and that the reason they switched to Linux in the first place was specifically because they were power users, and Linux catered to them better.
Now, the best software projects on Linux, ones that had previously been creating software that power users liked, and which became important at all because of the power users that switched over to using it, have apparently decided that power users are a minority segment of the overall market and that they are no longer worth optimizing for.
To make this clear: imagine if Windows, which currently is marketing itself to the "average computer user segment", a user segment that by-and-large were humans with some large subset of eyes, hands, and ears, and decided that the real money in the future was going to be branching out to take over the "any organism of any form" market.
Of course, that market has no real use for a keyboard or a mouse, as the majority of organisms don't have fingers. They can't see the screen, and they probably can't even reason in symbols. So the entire user interface starts getting converted into some kind of EM sensitive yes/no detector that is mostly useful for doing simple arithmetic.
Would this be reasonable? Would the people who currently use Windows not find this ludicrous? This analogy is obviously downright insane, but frankly I think it covers the situation here really well: the people who care about Linux are power users, so by forsaking power users they are forsaking their entire existing market segment.
For a simpler analogy, that I think also nails the core of the problem here while seeming really awkward: imagine if ALL the worlds best manufacturers of semi-trucks decided that cars were more profitable, and so decided to start marketing their products to them, not just by adding amenities but by making them less useful as semi-trucks.
So, over time, new models stop taking diesel, they force a back seat into the front, they add an optional trunk, and one they they decide to just remove the option to hitch things to the back at all. Would this be sane? This may even make sense on some kind of long-term strategy to take over the car market, but their market doesn't want a car.
Here, then: yes, I would agree with "the terminal is a power-user feature", but it is missing the point entirely to then argue that "I don't see any comment on the number of power users out there" here: claiming something is a power-user feature in order to justify its removal is indicating "small market segment", but power users are the market segment.