Let's make an example. You are playing in a gigantic galaxy and have ten starbases, named "Base ##", where ## is a number incrementing from 01 to 99.
Just to avoid confusion and automate the tedious repetitive tasks, you have set a rally point near each starbase, naming it after the starbase it is referred to (i. e.: the rally point near stabase "Base 06" is "To Base 06"). Nothing very creative, but pretty clear and self-explaining.
Now, let's assume yuo have also ten planets, each one devoted to build a constructor that should improve a specific starbase: so, planet XXX would direct its builded constructors to Base 01, planet XXY to Base 02 and so on.
Here come in handy the ability to command a planet to direct the ships to a specific rally point, when them are builded.
After all this preparation, for a reasonable number of turns you can nearly forget the entire starbases improving matter, being pretty much automated.
The problem arises when one of the starbases (let's say "Base 09") is completed (for the moment). You probably would to know what is the planet that was directing its builded ships to that starbase, in order to stop the production.
Well, the only way the game offers to you in order to accomplish this, is to call up the Governors window, select the "Colony Rally Point" option, scroll the left column for the colony set to the appropriate rally point (the "To Base 09" rally point, in that case), select "Nothing" in the right column and, finally, click on the "Update" button at the bottom.
Sure, this will stop the planet to build constructors directed toward "Base 09", but won't reset to "None" the default rally point for the ship builded on that planet.
Unless you intend to use that planet only to produce constructors for that specific starbase, this will turn into an annoyance (if not a little disaster), when you are - for instance - in need of building some defending ship and, having forgot to reset the rally point, you see them happily fly away from your threatened world; on the other hand, it is very difficult (or, at least, time consuming) to locate with precision which is the planet whose rally point have been modified.
Certainly, there is one (and perhaps, more than one) workaround: you can rename that planet adding the name of the base it is referred to. For instance, if the planet's name is "Cordelia II", you can change it in "Cordelia II - Base 09" and then look for it in the planet list.
But won't be more elegant (and time saving) having a separate window where you can locate each planet by its rally point and reset it to "None"?