Maybe it's just me, I can't help thinking the reviews were better until the under-performing US opening ("We can't go giving a good review to something that's flopped!")
I wonder what the expectations of Terminator sequels are. To me it seems obvious that Terminator - although well known - just doesn't have anywhere near the reach or number of fans as something like Star Wars. To me, that alone answers why The Force Awakens was going to make a whole load more, even if it was a copy of the original storyline far more than Dark Fate was.
Terminator 3/4/5 made $433m/$371m/$441m - all less than T2 (especially factoring in inflation), and not massive hits, but are they commercial flops? Other films (including series say The Expendables) have made less. It seems the problem is they spend so much on marketing for Terminator that it's hard to break even. (E.g., Wikipedia quotes a source saying Genisys needed $450m to break even - I don't understand how that comes from a $155m budget and $50-100m on marketing?)
The other problem is this repeated cycle where it's decided Terminator is a flop and the plans for sequels are scrapped, until a few years when someone else decides to have enough go, so continuity suffers. Imagine if Marvel gave up after The Hulk's $263m!
Well, I liked it, I'd be happy to watch it again. It suffered a bit of too many main characters making it hard for the new main character to shine through.
The idea of an evil AI rise being inevitable was covered in both T3 and the TV series, but it seemed better done here, e.g., that it would change which people were important in the future timeline. Cameron's vision for sequels was that Sarah would find a way to end this ever happening, and I guess we'll never see how now. (It seems to me the only options are to either prevent such a super intelligence ever arising by destorying all technology, or make sure that a good super intelligence arises.)
I was fine with not making John Connor part of it. There were already too many main characters. The first two films were really about Sarah not John. If people want to see sequels with John, that's Terminator 3/4/5. And I think they suffered because it's hard to show the reality of the character growing up into the myth that was made of him - especially in an altered future.
The idea of a terminator growing a conscience and living a family life seems funny, but I'm reminded of the scene in T2 where the T1000 has murdered John's foster mum, and is meanwhile at home cooking and preparing dinner.
That's a good point. To be honest, I took the intention to be that Terminator/T2/Dark Fate should be considered an entirely separate story, i.e., nothing in the other films or TV series were canon to this story. However, they did indeed make the "separate timeline" argument, and as you say, this doesn't work. Personally it's a pet hate of mine when writers use the "separate timeline" argument rather than just saying it's a different story (unless it's explicitly part of the plot, e.g., Star Trek's reboot). I can happily watch separate Batman film series without having to pretend they all exist in different parallel universes or timelines.