Honestly, Caves & Cliffs did add quite a bit but it is more in how to use features.

• Dripstone: It's mechanics allow for several new types of farms. Renewable Lava as one example
  • With 'The Wild' Update we can also now farm Clay by conversion of Dirt to Mud then drying it with Dripstone
  • Pointed Dripstone also provide us with the ability to make cheaper and more compact vertical traps
• Copper: It's definitely a mostly-decorative blockset but it greatly expands available color/texture range for builds into previously unrepresented Oranges and Blues
  • Lightning Rods are also a thing now allowing us to protect lightning-sensitive builds from strikes.
• Amethyst: Again is mostly-decorative however it can be used to craft Spyglasses which offer full-Vanilla zoom
  • Amethyst blocks also produce new sounds unique to them. This gained functionality with the advent of Wireless Redstone introduced with 'The Wild' update
  • Amethyst is also used in crafting Tinted Glass which allows us to view the inside of light-sensitive builds without letting light in.
• Moss: Another mostly-decorative block that actually has noteworthy functionality, fully autonomous Bonemeal Farms can be constructed with them.
  • Moss blocks also break quickly and spread over most blocks when bonemealed so can be used for excavating an area if you have a good Bonemeal supply.
  • Moss carpets don't burn which makes them the ideal floor for a Strider Dock as the Striders won't be cold (and thus trying to move into Lava) and you won't risk dumping yourself into the Lava
• Axolotls: Water-Dogs for those of us who want NPC backup while underwater like we can get on land with tamed Wolves. (As some of the C&C Update's artwork shows this is great for dealing with Ocean Monuments)
• Deepslate: While it's longer break time than stone is annoying it has higher Blast Resistance as well which can be useful in niche cases when building with TNT
• Powdered Snow: A new overworld hazard to make exploring a little more interesting and give Leather Boots a tiny buff.
  • Powdered Snow also allows us to convert any Skeleton Farm into a Stray Farm to more easily collect Arrows of Slowness *Dripleaf: Gives us one more tool in the creation of challenge/parkor maps. A very easy-to-use temporary platform.
• Glow Berries: A type of farmable food native to the underground which is useful but not challenge-removing for self-imposed challenge runs.
  • Their vines are also climbable offering a potentially earlier hanging ladder to Crimson Vines

Sure, none of these things are as impactful as Redstone itself was but they're all new mechanics that allow us to either interact with our worlds in new ways or make some ways we already had cheaper &/or easier.

I don't really feel all the updates before Microsoft always changed that much. I think the cave update is kind of cool because it adds so much more height to the world which is pretty cool, I'm just glad the game is still being updated after all this time. but personally once you have figured out most of the game it's hard to get back that feeling of when you first started, when everything was new, I think that's why valheim is doing so good right now, it's kind of like playing Minecraft for the first time again

The updates have definitely gotten less substantial, but to me Minecraft has always thrived as a platform for mods and other fun ways to play. The base game imo is more geared towards hooking a young audience and giving a fun, creative, if shallow, experience that's easy to pick up and get to grips with. If you want more in depth stuff there's plenty of complicated mods, and if you're clinically insane there's always Gregtech. Yes Microsoft has pretty much only done aesthetic upgrades and I really miss y:12 strip mining but I've also accepted I'm no longer the target demographic of Minecraft's and that's okay.

I'm actually quite liking the new content they're doing, but I get the same feeling, the new mountains and caves are REALLY cool, but I never did mountain climbing even with the older mountains, same for those submerged caves, I don't think I will explore them ever.

That said, the warden and everything related to him is really fucking cool and I love it.