Apropos of complexity, I am not so sure that the pendulum, as it were, has swung away from complexity that much. Mid-to-high-complexity games, from D&D to Pathfinder to Warhammer, still have massive player bases, after all. Shadowdark has been pretty popular - but so have Daggerheart and Draw Steel, which are both more complex.
Apropos of crunch "vs." roleplay, which seems to be an emerging subthread:
Example #1:
I was filling in for my brother in a D&D 5e game, say, two years ago. He had a gnome barbarian, they were playing Storm King's Thunder, and the party had recently triumphed against a pair of fire giants, with the barbarian being instrumental in slaying one of them.
So, when they went to a gambling boat, I made a point of having the character boast to NPCs that he had killed a fire giant. This led to an arm-wrestling challenge from a goliath, which the DM structured as a best-three-out-of-five Strength roll-off - I believe Strength (Athletics), though I don't recall exactly any more.
DM ruled that I could rage for the duration of the arm-wrestling match, giving me advantage on Strength checks. I flubbed the first two rolls despite it, then came back to win the challenge. We were all very excited by the result - me most of all, and I rose up from my seat, arms in the air, shouting "I killed a fire giant!"
(It was also a great way for the barbarian to contribute meaningfully to the social scene.)
To be sure, I would have been entertained by a different result - perhaps buying the goliath a drink with as much good grace as I could muster and then spending the rest of the scene sulking whilst having onlookers politely or not-so-politely laughing at my assertion, only to carry a grudge against the gambling boat and its folks for the rest of the campaign - which would have then paid off when the group returned later and ended up getting it shut down.
Example #2:
I'm playing in a Spelljammer game my brother is running, and one of the other party members is playing a fairy (from Wild Beyond the Witchlight IIRC) who happened to make a deal with archfey belonging to the Gloaming Court, seat of the Queen of Air and Darkness.
His character wanted revenge against the person who wronged their parents (the character is non-binary, the player isn't), although they saw it as justice - having, rightfully, felt that the formal systems of justice, such as they were on the Rock of Bral, had failed.
The fey agreed to enchant two of the character's pistol bullets to inflict unimaginable pain on their targets. The price was that the character had to cause harm someone they loved.
When we finally slew this villain (who had fallen in with a cult of Elemental Evil), she ended up dying instantly, turning to stone, and exploding; the character ended up losing out on the emotional payoff of their revenge, while still being on the hook to the archfey for their own end of the bargain.
As a group of players, we're still riding off the satisfying arc the game mechanics dealt us: a character hell-bent on revenge discovering that it is a bitter fruit of futility is meaty stuff!
Conclusion:
All that is to say that I do not see any conflict between complexity of rules and quality of roleplay - indeed, in both examples I have provided, the mediation of the mechanics actually made for better roleplay than I think we could have achieved otherwise.
I should think, however, that complexity of rules eats up the time available for roleplay, and it's well and good if folks find that bothersome.
