Ah, how I wish it were that easy. Yes, school assignments and homework could (and should) be made more fun and engaging but the reality is that life is chock full of linear, contextless, boring, repetitive tasks with no-immediate-feedback that must get done. I'm not saying it should be this way, or that homework should be shitty to prepare kids for reality, or that kids should be adults at 11, or that adults shouldn't have fun and eliminate every bit of useless dreck from their lives that they can. I'm not saying any of that. I am saying that sometimes you just have to grit your teeth and get shit done, no matter how unpleasant. That habit seems to often be learned at an early age. The most unproductive people I know still haven't figured it out, and instead go watch TV or play video games. And then wonder why they haven't accomplished much at 40.
I am assuming you are implying that the real purpose of school, then, is to teach kids to "grit [their] teeth and get shit done, no matter how unpleasant." In other words, to teach kids self-control. Reminds me of Robin Hanson: http://www.overcomingbias.com/tag/academia
Actually, I specifically said that's NOT what I was saying. I do think that there's a lot of stuff that should be taught in school that will never be as engaging as a well-made video game. It's just the nature of reality.
There's a difference between what you want to communicate, and what the words you type end up actually implying. I understand that you said "I'm not saying that [...] homework should be shitty to prepare kids for reality"—but saying that there are shitty things that should be taught, because that is reality, is the same idea behind a different facade.
We live in a socially-constructed reality. There are laws of physics and biology that say how the world around us acts, but really, we get to decide how we act, and make the rules for human behavior. If you entitle a group to an idea, make them think it is perfectly deserved—even if their own elders can't give them that thing—then, when they grow up, they will give the generation coming after them the opportunity they never had.
Entitle children to the idea of human rights and, having grown, they will not own slaves, and free those passed down to them. Entitle children to game-designed work, and, having grown, they will believe that game design has a place in I/O psychology, and that any organizational consultant worth hiring will need to optimize for fun.
Now, you might rebut with "but what about those laws of physics and biology you mentioned? Surely they necessitate some form of un-fun?" The interesting thing about that is, evolution has made sure that all the things we have to do to survive and reproduce are fun already.
* Running (and hunting, catching, killing), and exploring (and gathering, washing, preparing, and cooking) are both fun.
* Having sex is fun (think about how arduous procreation would be if evolution didn't make us think otherwise!)
* Being creative (telling stories, doodling, humming a melody to oneself) is fun.
* Competing and collaborating are both fun.
* Inventing and using tools is fun, as any programmer would tell you.
* Understanding why things work the way they do is fun (and funny! Laughing is the basic response to a sudden realization that makes you dump cache and re-parse a narrative.)
Other examples abound—the only things that aren't fun are the things we force ourselves to do to live in this strange, post-agricultural lifestyle—commuting, being "objectively evaluated", producing things that disappear into an aether and for which one never receives feedback from the people on the receiving end... we're not going to change this process from the end-side. School beats people down and makes them accept this kind of life, and thus they won't bother to change it once they get there, even if it could be better. We need to entitle these new people, to make them angry that they aren't getting something because it doesn't exist yet, so that when they get the power to do something about it, they will.
Your examples of fun seem terribly biased. I notice you didn't mention agriculture, which is probably a more common source of food for most of human history than hunting (maybe not, I'm no anthropologist). Like a lot of other things on your list, I imagine that agriculture is "fun" pretty seldomly, but mostly just hard work that is often quite dull and boring. You might get some deep satisfaction out of them, but I get satisfaction out of doing many things that are hard and non-fun at first. Your list feels very cherry-picked.
Sorry, I just don't see any way that an objective observer would look at the whole of human existence and conclude that evolution has optimized everything we need to do for survival and reproduction so they're fun!