The ones that have officially done away with ED2 that I know of are Northwestern, Tulane, U of Rochester, and Rice. I’m sure they all had their own reasons for going to a single ED round, but in the case of Tulane I’m fairly certain it is because of what I described above, which is that they could fill the class 3+ times over with qualified applicants in the EA/ED deferral pool already.
Unofficially, and again not publicized by institutions, I still firmly believe that ED2 will continue to be a hot button as it becomes clear that pool at many very good schools is filled with “high stat rejects” (said in the most complimentary way of course) from the top tiers where numbers simply can’t accommodate them…but who for whatever reason we unwilling to commit ED in the first place.
This is my educated guess…