Maybe you're not looking hard enough.

Again, I digress: changes like these would fundamentally change the nature of combat in Minecraft and make it much more complicated - likely too complicated to belong in the game. I'm sure I'll get a comment like "Minecraft is not an MMORPG".
That doesn't mean examples of making combat more skillful don't exist.

A big way to allow skill in combat to shine is add variety. Enchantments and potions were a big leap in the right direction, when before you pretty much just had full diamond-armored players fighting each other with diamond swords, you now have some room for individual preference with offensive and defensive enchantments and potions.

Yet there's still a lot more that could (not saying SHOULD) be done with the combat system in general.

Weapon Stats

• Rather than a standard progression of stone -> iron -> diamond, with each new tier having higher attack speed and attack damage, what about a more varied system?

• Dropped/looted (non-crafted) swords and bows could have random attack speed/damage scaling, perhaps within a set range or quality based on where they were looted.
  (Mob drop > dungeon > abandoned mine > Nether dungeon > stronghold > end ship). With an anvil, any weapon could have these stats be improved with an anvil and certain reagents (crafted whetstones of various tiers, or maybe additional ingots).

• Even better, maybe there's no way to "max out" attack speed and power to their highest possible levels on the same weapon, so players would have to choose one aspect that they prefer. Some players might forge a sword that hits very quickly, but does less damage than the "default" sword. Others could have a bow that shoots very powerful shots, but takes much longer to reload. Or you might yet be satisfied with a weapon that splits the difference, most similar to the system we have now.

Choose Your Weapon

• If done properly, a wider range of weapon types in Minecraft would certainly make combat more interesting and diverse.

• Imagine this: maces with lower damage, but a chance to immobilize enemies; axes that have low attack speed, but ignore a certain percentage of the enemy's armor; spears that do more damage with momentum or could even be thrown. Other weapons could pull and dismount enemies - halberds for melee, harpoons for ranged. Flails would be slow, swinging weapons to deal melee damage in an area. Sword variations, like short swords and katanas, would lose/gain attack range in return for better armor piercing / lower durability and power, respectively.

• Ranged weapons need variety, too! TNT combined with slime balls and spider silk could create "sticky bombs", sacrificing raw explosive power for the ability to toss one onto a wall or ceiling. Crossbows, which could be reinforced with the different metal tiers, would sacrifice the bow's precision and knockback for the ability to reload faster. Existing bows could get a variety of new arrow types - from realistic (fire/poison arrows) to magical (slowing slime arrows/Withering arrows).

• Different types of shields would offer different protection against piercing damage / slashing damage / crushing damage / arrows / magical projectiles / explosions. Depending on the type of shield and the material it's made out of, these shields could affect the speed of the player.

Swordplay

• For the actual act of combat itself, rather than adding new weapon mechanics, something as simple as a "hold-to-charge" melee attack would work wonders. A single click would be the fastest and weakest attack; holding down the mouse like for a bow would grant you a slow but powerful slam. In PvP especially, you'd have to constantly decide how much power your swings should have.
• Parrying would be a unique addition to PvP: if you swing at the same time as another player, neither attack would go through. A "dagger" or "knife" weapon could be dual-wielded with another dagger, an axe, or a short sword, and could block attacks without the use of a shield.
• "Advanced techniques" could take melee combat to the next level. For example, a quick left and right-click within sufficient range could disarm a player who didn't block or parry in time.
• When paired with weapon stats mentioned earlier and parrying, you can truly begin to diversify combat. At the risk of becoming too much like an RPG (I mean, we got over XP bars and enchanting items, right?), you could now choose between the classic "fast but weak dual-wielding" and "slow but strong greatsword-wielding" in addition to the typical sword and shield.

Other Additions

I have plenty of more ideas for how to make combat more interesting or skillful, as do many others. Here are just a few off the top of my head.

• "Snea