Mines are OP. Period.
So far here are the arguments for mines
infiltration units OP
Possibly. Haven't played enough lately to have much of an opinion on them strength-wise but some maps have a shitload of buildings all over the place and they make it too easy to harass. The answer isn't insta robbing the player that called the unit in though, its increasing the cooldown, or cost, or combat effectiveness, or something of that nature. Two wrongs don't make a right.
use a sweeper you n00b
That only encourages blobbing more to keep all your units around the sweeper unit. Or you could have two smaller blobs with 2 sweepers. Having every unit with a sweeper at all times is not a viable way to play the game at a high level. What if sweeper unit gets focused fired and retreated during a major push, but you still have the momentum. Now just put the brakes on until he returns because otherwise you could lose an entire squad? I don't think so.
An important principle of real war that also applies to games like COH is economy of force. For all you uninitiated out there, that means bringing just enough forces to one area to ensure that you win the engagement, so that you can hold a bigger front, and not overcompensating in places where you shouldn't. In practice that means not wasting time by sending 3 Shocktroops to hunt down one pioneer that is back capping, or bringing something more powerful than a rear echelon to deal with a harassing Obers. When done properly this means you will sometimes have multiple units operating solo, like sending 4 upgraded riflemen to deal with 4 isolated capping Gren squads (assuming the vet and/or weapon upgrades are in your favor).
Dividing your forces properly to capture and hold as much ground as possible is an important skill, which is much more difficult to master than taking 2 seconds to lay a mine. When the amount of front your army is capable of contesting is constrained by the fact that you don't have 2-5 sweepers, that is a problem. Now when you send off a bunch of solo units, it is an expectation that you will hit some mines, but those should only force you retreat and concede that area temporarily, not lose an important unit.
*This is really important. Dividing your troops up correctly, and having the micro skill to multi-task them is the single most important skill to improve at COH. Blobbing your shit to cut down on squad wipes is really detrimental to gameplay. Increase skill gap= profit!?!?!
it takes time/skill to lay mines
It takes no more than 2 seconds to locate a unit that can lay a mine, 1/4 of a second to hit B+M, and ~1 sec to choose a spot and click. You want more skill in laying mines, then reduce the time it takes to place them and the good players will get more mines down. Right now your bottlenecked primarily by the very long construction time, not the lackluster micro requirement. Obviously I don't want more mines until they have been reworked, that needs to happen first.
It rarely happens
Not that rarely. Sometimes you might go several games without it happening, and in my last 2 games (total 30 minutes of playtime) it happened 5 times total to either me or the other guy. So in my last two games, it happened about every 6 minutes. This isn't "shot down plane nuked my army" rare, the mines always kill everyone in blast vicinity, therefore squad wiping 100% when you hit it the right way.