Yes, I'm sure that is one of their design criteria.
If you think it's not, you're crazy. It's a constant tug of war between the software guys wanting more power for new features and hardware guys saying that the battery life will be crap. Add more battery capacity and the software side will expand to fill it. Or have you not been awake to watch the computer industry for the past 30 years. Gee, isn't it weird that your computer still takes roughly the same time to boot and load Word as it always has?