I've definitely noticed that "not reading sheet music" and "guitar" are concepts that go together, but I have to ask "why do beginning guitarists not learn sheet music?". It feels something like algebra, where some percentage of the population just look at a different notation with some abstractions baked in and immediately decide it's not for them.  

I've been learning acoustic guitar for a few months now, and strongly agree with all of this.  There are a lot of resonances with rationality practice here, and it also points out some difficulties that I had not realized.  Rational thought takes at minimum tens of milliseconds, which is notably less than how long you have to take actions when playing guitar.  Also these actions don't map in any way to evolved reflex loops (unlike, say, driving or juggling which also have similar reaction time requirements). This means I've had to explicitly figure out how to chunk and cache rational thoughts prior to playing, so as to be able to use them during play.  Music also allows many opportunities to look back at something you learned and say "How could I have learned this faster"?  You'll find that many people will tell you "You just needed to practice that for hours" for things which you actually could have inferred rationally very quickly if you had stepped back and worked the issue.

Deep geothermal energy production via microwave drilling to 20km.  If we can geothermal wells to those depths, we can pump down water and get back superheated steam.  This can then be turned to electricity using a standard power plant turbine.  In particular, it can be turned to electricity using existing turbines at coal- and oil- fired power plants, allowing those plants to continue to run but "defueled".  Abundant power, no CO2 or other emissions, no additional land usage, no intermittency, no additional grid connections required, no additional earthquake risks (it's drilling, but not fracking), no geographic restrictions (if you drill anywhere it's hot enough) which also means reduced geopolitical conflict. If you feel like it, you can use some of the waste water for wicked-awesome artificial hot springs like they do in Iceland.  The trick is that drilling to that depth is difficult with standard drills, so the idea is to use high-powered microwaves to essentially vaporize the hole down to the necessary depth.  The microwave generators necessary were designed for fusion research.  They stay on the surface, while the microwaves are shot down a wave guide (a conductive pipe, essentially).  Quaise Energy is hoping to have a test well this year, and to be defueling existing power plants by 2018.  If there's a downside to any of this, I haven't heard of it.

If you find yourself at a stage of life where you have multiple domiciles, I strongly recommend buying duplicates of literally everything that isn't literally one-of-a-kind.  Travel where everything but the clothes on your back and your laptop is already pre-positioned at the other end is a treasure.

is there any aspect of human existence as complicated as romance

Yes. Parenting and politics. Given a good enough model of humanity, you could probably prove that romance comes in precisely third after those two. Unlike romance, it's not even all that sensible to consider those two with non-sentient NPCs, a sign of their inherent complexity. Otherwise, good argument.

I'm coming in late, but I will say that you should probably examine the game-design literature. They are (for good commercial and aesthetic reasons) pretty much in line with your theory of fun, and in some ways advanced of it.