I've seen this type of argument in many places and over many different things, from tanks to jets, auto shotgun to sticky bombs, even blind eye to off the radar, and none of it has ever made any sense to me.
I look at it like this: you take the time to achieve higher ranks in order to unlock more tools of the game. Why should it be an issue when you choose to use the tools you're availed?
Personally, I tend to only use my minigun when taking on tanks and aircraft...otherwise, I'm not really a fan of the gun. That said, I have no problem if a player wants to use nothing but the minigun...if that's what the player finds fun, so be it...they're not breaking any rules, so there's nothing to have an issue about.
People definitely need to stop complaining about items being "overpowered" as well. A skilled jet pilot should be able to wipe the floor with someone on foot. Tanks should never have been adjusted (I miss the old "Oh sh*t!" factor when a tank would roll in and you're on foot...now, I find I end up running TOWARDS tanks because it doesn't take much to stop one anymore). The auto shotty should put someone down in a blink. And the minigun should rip you in half.
Remember, you always have to option to remove yourself from a session if it bothers you so much that someone is using a tool you don't like.