Anybody who knows anything about MBTI type will tell you that E/I is actually the least important distinction.
Even in Jung, Fe doms are the only stereotypical extroverts, seeking people at every turn.
Typing people, in general, becomes frustrating when you differ on constitutes a type, whether you follow Keirsey ("expressives" for example, versus simply having an extroverted perception) ...apparently BECAUSE I WRITE A LOT, I'm an extrovert on-line.
HOWEVER, Jung makes a very very particular distinction between J doms and P doms, and how they view the world; and it makes a huge difference to be ENFJ or INFJ, to be ESFP or ISFP, for that reason.
J doms have a "rational" view of the world, and P doms do not. P doms see J doms as limited or closed off, and J doms can see P doms as easily swayed or even inhuman.
That's why in some theories, ESFJs are supposed to be with ISFPs or ISTPs, and so forth. It's not just because E and I supposedly "balance" each other, it's because two J doms have a more agreeable world view, even if it's a different judging function.