If PSI exploits weird physics in a complicated manner and produces such tiny effects, where the hell did the mechanism come from? PSI would obviously be a very useful adaptation, so why don't we see it in other species? Why aren't the effects stronger, since there's such a strong evolutionary pressure in favor of them?

All of this is also discussed in Outside the Gates. I can try to dig up what he said this weekend.

Goertzel's paper also includes psychokinesis as a PSI phenomenon supported by strong evidence. I would love to see the study he's talking about for that one. Or a video.

The experiments aren't macroscopic. The results involve statistical deviations from expected normal distributions of say, white noise generators when participants try to will the results in different directions. I don't think these results are nearly as compelling as other things, see Jahn and Dunne 2005 for example. They had some methodological issues and the one attempt that was made at replication, while positive, wasn't significant at anywhere near the level of the original.

If you're actually interested you should consider checking out the book. It is a quick, inexpensive read. Put it this way: I'm not some troll who showed up here to argue about parapsychology. Six months ago I was arguing your position here with someone else and they convinced me to check out the book. I then updated significantly in the direction favoring psi (not enough to say it exists more likely than not, though). Everything you've said is exactly what I was saying before. It turns out that there are sound responses to a lot of the obvious objections, making the issue not nearly as clear cut as I thought.