Much googling and perusing the forums, I am not alone in this thought.
The way it works right now:
Parent task Time Tracking, before logging against a subtask:

After logging 1 week of time to a subtask:

Surely many many people do not prefer this behavior. Can we please get it so Parent "Remaining" is reduced, instead of its "Estimated" increased?
My company, and I'm sure many others, dole out large chunks of time for a sizeable project. This would be the parent task. It only makes sense to then break that up into more manageable tasks, aka subtasks. The work against those subtasks would subtract from the total available time allotted to the project, i.e. subtract from parent's Remaining.