there's a lack of consistency - why have a message which warns the player that they've bought an item which needs to be added to a Firegroup? Why not let them fly off into space to take on an Anaconda, then, when they fire, oops... one pulse laser and the rest aren't set.
Yes, you are right about consistency. I would also remove the warning about the firegroup too. It is the typical "I-hold-your-hand" warning that the game does not need.
If you buy a weapon or something that should be used the same way the first thing is always to check your firegroups just to make sure they are really there and when you are there you are also realize if you need to assign it to a firegroup or not.