Right Larry,
The Rea plugins were so GUI challenged, many of the programmers came up with slick and beautiful faces almost as an apologetics for how they represented graphically. Slick GUI's available for some of the js plugs among the resources on their web page. Did nothing for the function of the plug, but presented it in a hi class lipstick that gave it credibility to the mind of those needing an elegant interface. Me affected as well. If it is that great, needs to look great.
For reference only as far as plugin formats, we got what... Vst, ax, dx, rtas, whatever else out there.
Reaper devs did a beautiful offbeat approach, though many damn them to the brimstone pit (and have already) for **** with that which is philosophically off limits.
They wondered, what if Jesus were reincarnated today, and was a rock musician. He blundered into Reaper to record some church music. What would he go to for effects plugins.
Thus the vast expanse of native *js plugs included in Reaper. Jesussonic.
Not compatible with any other DAW, but there native in Reaper. So many of them. The ReaPlugs you mention are a vst translation of the *js natives (correct me if wrong). Butt ugly, but the guts are there. All are not gems, so you have to sort through them. If you are a programmer, the js plugs can be opened in a notepad editor and tweaked to your specs. Can't do this with a vst.
John