It must be a huge inconvenience to see the obvious incompetence displayed while assessing the performance of the flight crew from your seat in 36F!!!
On these occasions where you have experienced such hesitations in taxiing could you provide a little more detail please. Ideally of the airfield layout, the notams of the day regarding taxiway operation whether any additions were mentioned on the latest ATIS and how these related to the ATC taxi instructions provided. It would also help if you could describe the flight crew's familiarity with the airfield. Only so we can sit in the comfort of our own homes and judge the professionals with the same information you must clearly have had.
As for intersection take offs...Perf A calculations and NO airline SOP's countenance using runway ahead after V1 for stopping, so if the calculations show it is within the aircraft performance to use ANY intersection and it will save some time there is no valid reason why it cannot be used. ATC permitting of course (in fact often it is at their request!). Runway behind and fuel in bowsers are all wonderful generalisations of single engine flying. They do not apply in the commercial world where the decisions are much more considered and calculated.
Also as for 2,3,5 minutes not being important...safety is the primary concern following that is commercial expediency. Sometimes by not being able to take the intersection you may need to wait 15 minutes while 4 aircraft arrive and 2 depart from the full length. Did you have the big picture on the occasion or your intersection departure? Was the full length even available on that occasion?
So many questions slip and turn, and so many answers which I'm sure were clear to you from the cabin!
Happy flying.
Jazzy