That's mostly because resetting TAG to continue using it after suiciding the "pilot" is not very intuitive at first. I assume it's the same for manned TAGs?
Visualize it a bit like a limited version of Jumper. The pilot's controlling the TAG... Then the Crabbot... And if the Crabbot dies he can jump back into the TAG, but requires a WIP check to do so. The Crabbot isn't a pilot, but rather a drone that requires the pilot's concentration to use. It's primarily there to push buttons, but stepping on that e/mauler is pretty helpful too (if you're willing to spend the Orders on it.)
It's not like I can't explain stuff away, it's that most of the time when you do so you risk dropping some important detail in the rule that doesn't support your vision of common sense due to actual RAW you moved your focus from. As such, I prefer to just keep memorizing rules proper instead of coming up with mnemonic tricks based on common sense. Especially when it comes to a minor mess such as rules for multiple profiles / mount / dismount / equipment-as-profile when all those meet in one place. Only methodically cracking one logical point after another gets you anywhere.
