In many ways a lot of the sets, even with the amazing building techniques designers can use now, diminish the original ethos of Lego being "imaginative play".
Yeah, I feel like there's a lot less emphasis on imaginative play as there is on 1:1 accuracy and high detail. Now that isn't bad, but I like when it was reserved for a couple sets a year, like a massive UCS Star Wars set such as the Death Star or a modular building. Now it seems pretty near every set has that focus, and they're always big with few good small-medium sets. This in turn diminishes the value of those large, exquisitely-detailed sets with oversaturation.
I recently built a Chima set from 2014, and I was shocked by how there was a much greater emphasis on playability. It had a dropping gate, exploding stairs, and a trap door. The last set I remember having such playability is Emperor Unagami's temple from the Ninjago Prime Empire line, though it seems that the new 4+ Spiderman Green Goblin lighthouse set also has that kind of playability with a trap door and rollercoaster tracks.
I also wish Lego was putting out more original themed sets instead of everything being a licensed collectors' tie-in. We should be having an original space theme, an original castle theme, an original pirate theme, and a rotating assortment of several original action/adventure themes. Keep giving us weird, short themes like Power Miners, Dino, World Racers, Time Cruisers (I like that Dreamzzz seems to be a modern Time Cruisers), and Agents instead of picking up yet another license. The trend of the 3-year big bang theme seems to have also died out with the failure of Hidden Side (it failed because it leaned heavily on app interaction as a play feature, something Lego seems to be moving away from finally); I personally loved those themes (Chima, Nexo Knights, originally Ninjago) with unique ideas supported by cartoons and lots of lore. Hopefully Dreamzzz is bringing that back. It seems that they're funneling all their original theme ideas (space, mining, underwater) into City, so while it's nice they're keeping those themes alive in a way, they have to be more realistic and can't do all the cool fantasy stuff. I've heard that they're precluded from doing space and castle because Star Wars and Harry Potter count as space and castle, though that's no excuse for not making a new fantasy mining theme or a new Aquazone theme. It's a shame because based on that Lightyear starfighter (which is one of the best sets of the decade so far in my opinion) they would absolutely knock it out of the park with a new original space theme.
Maybe Lego is focusing so heavily on the licenses because that's just the overall trend in toymaking nowadays. Whenever I go to the store, there's barely any new toylines not based on movie/TV licenses, which is pretty sad. I guess there needs to be a recognizable license for kids to play with a toy nowadays and not run back to their iPads. Plus, there are plenty of 35-year-old engineers who have lots of disposable income to consoom toys, and this demographic wants recognizable toys for the nostalgia, so nothing original is being made.
Occasionally I'll buy a speed champions set because they're fun builds, compact and relatively inexpensive.
I like Speed Champions, but given that it's basically modern Racers, I wish they focused more on new fantasy cars rather than real-life cars and movie cars. I personally like the Mega Construx Hot Wheels line for this reason, because they make lots of fantasy cars. I also wish Speed Champions had mini cars and stunt sets like Racers had with Tiny Turbos; those were super fun, if for no other reason than that they were better urban sets than City sets.