I think having all races' mines drift towards enemy ships is a good idea in theory, but there are a couple obvious problems with this idea.
1. If they were placed on the Zaxis and they began drifting towards a ship, they would be slowly drifting back to a 2D formation.
2. Drop a few scouts in just before the fleet and "aggro" the mines, and then lead them around in circles or at least to the opposite side of the GW. The only way to prevent this from happening to destroy the scouts as fast a possible, but a fleet of 20 scouts could easily make it to the opposite side, and if you send your fleet/sc to go get them, you're leaving part of your GW with less defense/undefended completely. Giving the enemy even 30 seconds of easier attacking could be a deadly mistake.
A possible solution is to have the mines pick a random target, and give them a ??% chance of changing their target to a new ship that just came in to the gravity well to make some of them target the actual fleet. A counter to this though is once again using a few scouts to constantly(in a staggered rotation and at various coordinates) be entering/exiting the gw to draw the majority of the mines' attention. This would require a bit of effort by the player, but it would give you enough time to do significant damage to the enemy without thinking about mines. If the % were too low though, the original scout fleet could keep them going in circles unless the enemy focused their attention on the scouts. As I said before this could have dire results.
The removing icons idea is the only viable idea imo, despite making mopping up a pain. Giving them a higher targeting/aoe range could also help, but the devs would have to be careful to find the happy balance. Too much range makes entering a gravity well instant death for your front ranks, too little range makes what we have atm.
