As for fears of confusion, many birders still use the guides and taxonomy they first bought/learned 20 years ago. While over most of the range this isn't a problem perhaps, there are certainly areas where it would be. 30 years ago this didn't matter much, but with ebird it now does, since if Mew Gull wasn't changed to Short-billed Gull, every ebird reviewer would have to spend a large chunk of their time querying Mew Gull reports to figure out what they actually referred to. I have heard many many ebird reviewers make these sort of rants about the Winter/Pacific Wren issue, and this is why Ebird I believe changed the Ebird names for the moorhen splits, because they were getting tons of "Common Moorhens" from all over the country, when it should have been Common Gallinule.