You're overselling it a bit.
You don't need to play the first game to understand the dynamics between those characters; the second game does a fine job of setting up their relationships. The first game's MC gets closure in that game and not the second one. As for seeing another perspective of Jowston in 1, maybe, but it's not that essential. One is not missing "so much" on the second game by not playing the first one. Those things are very important to you because you're a super-fan of the series, but for the average guy who just wants to enjoy a great game, those things are superficial.
I played the games in this order: III -> V -> II -> I -> IV. I played 2 right after beating 5, and played 1 five years later. That did not prevent me from holding 2 as one of the greatest JRPGs ever (*cough* 5 is better *cough*).
Anyways, people should play 1 not because of its ties to the second game (as they are not that significant), but simply because it's a great game. Scratch that, they're all great. Even 3.
But not 4. Fuck that game.