I don't really have a problem with the size of the Plus phones. It's the size and shape I can't deal with. My Moto X is only slightly shorter and narrower, but thicker and with a slightly larger display, but it was always easier for me to use one-handed than an iPhone Plus. Now I have a Galaxy S7 Edge which has the same size display but is noticeably smaller and also much easier to use one-handed.
If Apple would go back to using flat edges or something with a big more grip, I could see myself maybe owning an iPhone Plus in the future.