Say you want to compare 2 compressor plugins on 1 track. Right now you have to bypass one, then un-bypass the other, so there's a gap in the comparison. It's A-C-B, not truly A-B. Or, you have to duplicate the track and put one comp on one and the other comp on the other; mute one track; put the 2 tracks in a mix group; click either mute to toggle which track is muted. Once you've made your choice, ungroup and delete the losing track. But this is very inefficient.
Better solution: a key/click combo and/or something in the insert context menu to "arm" the bypass functions of multiple plugins. Each insert you arm could turn haloed, for example. Then you just command-click 1 to automatically bypass the others. (And vice versa.) This would offer true, immediate A-B comparisons of plugin effects, in a very efficient manner.