To me, MBPs long ago reached the point where additional thinness provided no utility, or at least, was greatly outweighed by the utility of having more or better ports.
The 13" MBP has a 54Whr battery, the 15" an 83Whr battery.
https://www.casa.gov.au/standard-page/travelling-safely-batt...
https://www.faa.gov/about/office_org/headquarters_offices/as...
Lines 7-8: https://www.phmsa.dot.gov/safe-travel/batteries
In your FAA document, page 2, line 3.
I’m finding it hard to see a scenario where I would prefer a charger over a little additional weight on the laptop itself.
But guess what? It doesn't really matter. I'd still pick the 2014 chassis if it was specced the same as the 2018.
I do hope the next chassis will fix the keyboard and maybe even add back the sd-card reader, not to mention introduce top spec non-touchbar models.