It's not just for bulk upgrades - but taking an old design and clicking on various bits - inserters, assemblers, modules, beacons... to tweak it up or down one quality level at a time. Like going from fast inserters to bulk inserters! (you don't have to worry about rotation either!)
(Upgrading belts and pipes for quality though, fair enough that's fairly useless)
In all of our playthroughts we were always choosing different kind of items to be upgraded at different times based on need, and then we upgraded the master upgrade planner to reflect that. The master upgrade planner could be used anywhere, even repeatedly, and it always upgraded stuff to the current tiers. Having an upgrade planner which upgrades everything to the next tier is quite theoretical need, the same as the current feature of an empty upgrade planner which upgrades evertyhing to the next tier of thing (normal belt->fast belt etc)