I'm not sure there is a another coordination problem that offers greater returns than this.

Also, after the point where hobitisation is moderately common it should be in the interests of individuals to  become hobbits. Most of the gains (cheaper housing, longer life expectancy) aren't externalities. 

I think this is kind of the perennial problem for any nominally altruistic group. I'm not sure how you'd insure against it or how'd you'd even know if it was happening, but I definitely agree EA should at least acknowledge the potential problem having large sums of money and prestige flow through the organisation creates, more so than it currently does. 

Personally I think Orwell was wrong that the Soviets' main problem was Napoleons' greed (don't ask me what the real problem was), the semi-recently opened archives give pretty clear evidence that at least the members of the politburo where believers in their cause. So maybe corruption isn't actually very common in real world altruistic organisations.

If the Robin Hanson type future happens then probably very little we do now would end up mattering, except maybe avoiding extinction risks. In that sense Hobbitisation is the in the same situation as any other medium/long term proposals.

I was going to mention that as a limitation but it was already getting quite long.

I don't think that kind of constraint would impose a very hard limit in the minimum size, judging from evidence like: most people with dwarfism have normal cogitative abilities, animals like crows have intelligences disproportionate to their brain size.

It's still something to consider though and exactly how considerable a factor it would be could be an area for possible research. Could you make people pixie sized? for example.

Yeah it didn't really occur to me that that was what I was advocating till a while after I had the idea.

But I do mention that it's meant more as a proposal for a future scenario where eugenics(might be too strong/loaded a term) is considered acceptable or becomes inevitable because of competition between individuals. In that scenario it would be better to push heights down than up.

Still I think we should keep an open mind.

There might also be ways of reducing average height other than gene editing, which wouldn't technically be eugenics I guess.