This ^
You actually want the defenders to return the item quickly as an attacker because then you don't need to fight all the way to it only to have it return moments before you get there. If the defenders return it then you can safely regroup and pick it up again. it's unlikely that the defenders will be ambushing you at the pickup point.
The worst thing the defenders can do is wait for the attackers to respawn and come all the way back into the firefirefight before they return it. Now you've wasted all the time respawning, getting back to where you died only to have to turn around and go all the way back to the pickup point again.
It's a slightly risky strategy on the defence side but if they pull it off it is horrible. Of course if they couldn't return it at all it suddenly becomes a massive advantage to the attackers. And self-returning is only going to split the attacking team up as half try fight to where it is and the other half run to the spawn point because they don't think they have the time to get to it.
Actually, that is exactly what was happening to us last night. Couldn't even re-group because of it. I understand what you're saying though. Your point holds true vs bots, but against some decent players, it's harder than you make it sound.
My team was constantly being split up and spawning. If the carrier went down, forget, I don't care how close you are, they are returning it. Then you fight all the way back to the item spawn, only to lose a few players just trying to grab it again. Rinse and repeat. I'd much rather fight for it, carry it, and if it gets dropped, it's left there for us to go back.
If I'm supporting the carrier and he goes down, they return it, now I'm stuck in BFE. I could try and fight my way back out to get the item again. or stay and try to clear a path. Normally I'll stay. But either way it becomes a frustrating and boring part of the match going back and forth. I wish it worked like the escort objectives, when the hostage gets downed he stays there and his team has to fight towards him again, and defense has to set up to defend that. Think the same principal could make this objective more fun.