>whatever amount of money you would like to provide for good causes, a good case can be made to eliminate the middleman and provide that money directly to everybody -- no qualifying, no overhead, no gaming the system, no complex system of administration.

This is my main disagreement with UBI. Resources (money) is limited, and providing the same social help to all regardless of need necessarily hurts those most in need and helps those in the least of need.

Your argument to make a simple system can be applied to many places it makes life worse - should we everything and all at the same rate? Experience shows that progressive taxes is probably a big benefit overall, and certainly tax incentives can and do have benefits. I think providing basic assistance, since resources are not enough to simply give everyone goods, should be targeted to minimize human suffering, and providing free cash to those that can work in lieu of providing it to those that honestly cannot is inhumane.

You dislike the middleman, but again, middlemen are vastly beneficial in many cases, and likely are here too, to distribute limited resources in a way to do the most good. And the overall cost of the middlemen is small compared to the amount passed out. UBI would also require a decent amount of administration, so it's not completely without admin.

>I outlined the reasons why it looks attractive

Sure, free money untethered to reality is attractive. The problem is the attractiveness fades when one is tasked with explaining how the money is obtained.