Hi Jamal,
I think you have legitimate points with these two examples although we've deviated quite a bit from anything to do with the deprecation of the 3d toolbar tools. I discussed this thread with the User Advocacy Group and highlighted a number of your concerns/examples. They will be sure to discuss with the respective teams involved. My guess at what happened is the Explode UI command was in the software, then at some later date there was a need to automate the functionality, and another team created the GP tool and named it something different than the UI command. Just my hunch. Nonetheless, I see how it can create confusion.
The Planarize Lines command does actually have some GP tools that do the same. For example, Feature to Line can be used to split the lines at intersections. Depending on whether or not you preserve attributes you will retain the overlapping line segments (preserving keeps overlap). There is also a simple model that could be built that would incorporate Intersect (output type points), Split Line at Point, and Delete Identical (using Shape field). Feature to Line works on more than just line input which is probably why it's not called Planarize Lines event though it can do the same thing. At the very least, searching on the word Planarize should return better results. I will submit a NIM to the team so that additional tags are added to the Feature to Line tool for search purposes.
Thanks for your feedback.
Best,
Eric