Of course, not! They do it just for the lulz!
More seriously, for space systems and embedded systems in general, due to resource constraints on-board, you usually cannot fit all the functionality you would like to in one software image. So you keep only what is necessary for the first mission, and then you replace the obsolete ones with the next thing you want to do.
As a simplified example, when you launch a satellite, you will need it to deploy its solar arrays quickly (and do many initialization checks). When that is done, you could imagine changing this part of the software with something else...
Also, they might have had time planning constraints on the project, and needed to launch with a simpler first version of the software, while finalizing the second one. That does happen.