You are correct that, until 2010, many videocams allowed the user to shoot at various resolutions or frame rates. However, not many (or were there any?) allowed one to switch from NTSC to PAL, though you'd think this would be elementary. I vaguely recall that a Sony P72 camera allowed one to pick either format, but that was in 2003. Some editing products let one export to either format, to this day, though the conversion may entail some IQ loss.
People complained for a long time that some cameras omitted 24p. Some recent Canon mirrorless or compact models offer that only. That is a serious impediment if someone needs to blend 24p with video shot in 60i or 30p with another device.
Many recent dedicated videocams allow one to shoot at various frame rates or bitrates, but all at 1920x1080 resolution. The ostensible reason is that buyers are drawn to "Full HD" and don't perceive a reason to shoot anything else. 1440x1080i video is easier to edit, and looks quite nice on most screens, but probably rings no bells when the firms interview potential buyers. 1280x720 60p is arguably very good for action video, and (unlike 1080 60p) is compatible with the existing stock of BD players, but not a mode one hears people beg for.
Some Sony and Panasonic P&S cameras allow one to shoot in 1280x720 30p mode, either in MP4 or JPEG, which is easier to edit. This is an alternative to AVCHD. Buyers are probably naive to the issue at stake, though, and only a few probably discover the actual distinction, or take advantage of it, since lot of video never gets edited.
In brief, the answer to one of your complaints is simple "customer demand" for 1920x1080 and nothing else. Some buyers insist upon shooting only at 24mbps, even though a modest 9mbps might look nearly as good and edit more easily. Some people want 1080 60p video, despite the limited sharing options.