I would enjoy the enemy surrendering and giving you cargo, ships, etc. for allowing them to retreat safely.
There are various reasons why you would still want to wipe a fleet, however. Bounties, in particular, give you incentive to fleet wipe the enemy and/or if you have a commission and you get paid by how many ships you destroy. Pirates, too, will likely not surrender.
However if you're going against the major factions or looting trade/civilian convoys, letting the non-combatants go in exchange for faction rep (or less of a rep hit), commodities, credits, weapons, even undamaged ships, would add an interesting wrinkle to your decision-making. Maybe you're able to see what offer is "on the table" and can take it or leave it mid-battle. That is to say, if you reject it, you continue doing what we have now. If you accept it, the battle ends. Surrendering would give the player the choice of knowing exactly what they would get post-battle versus the RNG of salvaging afterwards.
Ideally, there would be various dispositions towards surrendering. That is to say, I wouldn't want the surrender prompt to occur every battle. Perhaps certain factions are more predisposed to surrendering while others are fanatics and won't under any condition. However, if it's only popping up 25-30% of the time, it seems like a lot of work for little gain.