There's one thing that amazes me about Minecraft, and that's how a simple, elegant game can be so absolutely fascinating. Minecraft doesn't have seven novels' worth of voice acting, it doesn't run on the Unreal Engine 3, it doesn't have achievements, it doesn't have an endgame, it doesn't have a leveling system, it doesn't have a story, and it doesn't have "The Epic Flaming Staff of the Silver Monkey Cheetah God."
"There are plenty of untapped ways to have fun without creating these overly elaborate systems or wastefully throwing your money at eye/ear-candy."
Secondly, Minecraft also proves that you don't need to hold the user's hand every two freaking seconds to make sure he/she understands your game. User-friendliness should not be confused with "make it so easy an eight-year-old can do it." There are still things about Minecraft that I don't fully understand, but it doesn't mean that the game isn't fun or approachable. Minecraft is simple enough for anyone to approach and deep (and understandable) enough to keep you playing for a good, long time. That's the mark of an amazing design.
Third? Killing is so, so, so, so, so overrated. Minecraft has killing if you want there to be killing, but I think everyone agrees that some of Minecraft's most appreciated features are the crafting and construction portions of the game. Surprisingly enough, games can be fun when they don't involve dominating your enemies on the battlefield. There is no reason that farming, crafting, or other types of non-combat activities can't be fun in MMOs, so stop making them so dumbed-down or non-essential. They don't have to be like that.
Minecraft is inspirational to me. It reminds me that games don't have to be carbon copies of every other title out on the market. It's OK to go your own way and do your own things. There's no law that states games are only about killing eternally respawning arch-villains for loot and achievements, so stop pretending like there is.
Seraphina Brennan, the Miner of Crafts, serves up her opinions in Anti-Aliased every week. When she's not rambling here, she's rambling on her personal blog, The Experience Curve. If you want to message her, send her an email at firstname.lastname@example.org, or follow her on Twitter through Massively and her personal feed.