As someone who usually sides against Apple-isms (see my previous comments), I can somewhat understand the logic a little. The analogy I can take is a water bottle, you don't typically consider the amount of water in "how many hours will this last me", you just look at the amount and tamp your drinking rate accordingly.
Even though the time estimate was not that accurate and that it constantly changed based on workload, I found it useful to get an idea of how urgently I need to plug my laptop.