Re: Longer battery life
I wouldn't carry a laptop and 4 extra batteries either.
Go back a few years, and that would have stopped you from being a mobile worker. I remember members of staff whose laptops had an extra battery in place of the optical drive, plus they carried 2-3 extra batteries when they went on business trips. It was the only way to get the thing to last more than a couple of hours.
And I obviously don't mean a smartphone that will remain unused, doesn't surf the web and doesn't receive email from either 2G/3G or Wifi.
I think you are asking the impossible. I have a Oneplus One and it has the best battery life of any smartphone I have had for several years. It has a large battery, but even it can only last about 2 days of moderate use.
To get what you are asking, they would need to triple the battery size. This would increase the handset's size and weight. When most people are OK with charging every night, why would mfrs ruin their handset by making them bigger and bulkier than they need?
And if you are happy with extra weight, you can buy a USB battery pack. Mine cost about £20, will charge 2 devices at once, and has enough juice to charge my phone 3-4 times, which would put my away-from-charger time up in the region of a week.
Or you can buy a phone with a removable battery, and a few spare batteries. I used to do this with my phones, and it worked a treat.