Or, in some cases — myself included — don't want to be on an unfair PvP fight at all. If I'm wiping the floor with my opponent, with no chance of him to recover, I will often leave the fight out of boredom. Winning when my victory was guaranteed isn't fun or enjoyable in any way.
Assuming all PvP is about challenges and fair fights is a wrong assumption, I agree. There is a whole class of PvP about setting up the fight to the player's advantage, trying to make the result a foregone conclusion before the first shot is even fired. It's a kind of PvP I could never enjoy, and I doubt I ever will, but I do acknowledge its existence.
But assuming everyone would enjoy PvP, or even that everyone that enjoys PvP can enjoy the kind of PvP where fights often aren't fair, is an even more wrong assumption.
Thus, allowing players to basically turn off those unfair PvP interactions is a very good thing indeed for the game and its longevity. Far better than chasing away players that either don't like PvP or are picky about it. More so because PvP was never a selling point of this game, not to the extent that being able to avoid PvP was at least.
And a small reminder: this game is supposed to be the successor of a series where PvP never existed. If the devs can't make the pure PvE experience at least as good as that of the 30 years old game that started it all, and that is still played (either in its original version or the open source remake) even today, they are doing something very wrong. This game doesn't need PvP in order to improve its longevity.
According to many players that trade in open, any half competent trader can make as many credits in open just by properly selecting routes that are both safe and with a good payout. So, no, no real advantage, and the whole thing is fair.
And that is even without taking into account that anyone in open is allowed to jump into a group, or solo, any time he wants. Which makes things even fairer.