From a competitive standpoint a stagnant meta is actually a good thing. Yeah it may be a little more boring to watch, but if you want to have the highest level of play possible so that the best teams win every time, then you want the meta to be as stagnant as possible. A stagnant meta allows players to actually practice doing the same thing over and over so they can get good at it and perfect it. If we start bringing in other weapons then the game turns into who can find the broken strategy first instead of who is better at executing/the actual game.
Look at sc:bw, the game was played with the same units/meta for multiple years and was extremely popular because it had such a high skill ceiling for execution.
In game lobbies will help grow tf2 for sure, but the idea that the meta is stagnant or that it is actually a problem is just silly to me.
Also I think if we actually want to start growing comp tf2 we need to stop identifying 6s and hl communities as different and merge them into 1 competitive community. This will probably never happen, but the current division between the two communities is nothing but harmful to both.