The strides Apple has made to make devices smaller, more efficient, and more powerful are incredible. Though they come with obvious downsides. Cramming all that tech into a small space means you don't have an easy "click to remove" battery cell any longer - or hard drive, or memory sticks, or floppy drive bay... ;)
Not to negate your point - battery lifetimes are quite poor compared to the lifetimes of all other electronics in a computer and making them easily replaceable would be ideal.
Do we want smaller, faster, more efficient computers, or do we want easily modable computers?
Obviously both would be ideal, just not sure if that's really feasible with the way the technology is progressing.