From where I sit, mines are fine to employ on behalf of players so long as they are very clearly marked on Side Chat Map and they are used in good faith with regards to the other players on the server. The problem is that I&A is not a tight, controlled environment where everyone is on the same page, with the same intentions. Whether it be players intentionally using mines to troll or players establishing a "mines and the players who use them are bad" mentality to justify trolling, there is potential on both sides for people to exploit another useful feature to worsen the gaming experience for everyone else.
Here it is in plain text, as far as I am concerned, if you place down a mine and someone else steps on it, it is your fault. It doesn't matter how many times you marked it on map or tried to tell people in chat, the teamkill is on you. They died because of what you did, simple as pie.
That said, in an environment where trolls don't complicate things and the appropriate responsibility is taken by those laying the mines, mines, yes, can be useful. For those wanting to use mines for the correct purposes, you should be able to go ahead and get it done, however you must understand that there is no excuse for others getting killed because you recklessly assumed that players gave a crap about the map, the chat and the other players around them. In a more serious circumstance, such as a pre planned and organised event, mines could find a particularly interesting place in the game. I&A is often not that serious circumstance. If you asked me, the mine is the mine layer's responsibility, if the other people in the server aren't playing ball, and are getting mine teamkilled for whatever reason, the solution is to stop using mines. If it works, great, if it doesn't, don't push it further than it needs to go.
Whether it be via making one specific class responsible for mining or specifically outlining their use in the rules, I do agree that there should be some clarification with what is and isn't an acceptable use of mines. Perhaps other staff members feel differently, perhaps not.