I can't speak for laptops but I can speak for the utility of having a thin phone and a battery pack that makes it thicker and heavier than it would be if Apple just included a bigger battery:
I've only used my battery pack four or five times in the year and a half I've had my 6s. Most of the time I'm not far away from a plug - either at home, in my car, at work, etc.
But when I travel, a slightly bigger battery wouldn't be enough. I would want twice the battery life - something I can get by using a battery pack - but I probably wouldn't get from a slightly larger iPhone.
If you have to optimize, why optimize for the edge cases instead of the most popular case and give options for those times people need it.
I've only used my battery pack four or five times in the year and a half I've had my 6s. Most of the time I'm not far away from a plug - either at home, in my car, at work, etc.
But when I travel, a slightly bigger battery wouldn't be enough. I would want twice the battery life - something I can get by using a battery pack - but I probably wouldn't get from a slightly larger iPhone.
If you have to optimize, why optimize for the edge cases instead of the most popular case and give options for those times people need it.