Amidst all the noise, complaints, dissatisfaction .... and occasional positive comments ...
I see folks saying "I am leaving and not coming back" ... or words to that effect .... and it doesn't make sense to me if someone actually likes the franchise.
Yes ... almost everyone is irritated with PGI for their slow progress in turning MWO into a real game instead of just a fun 10 minute rinse and repeat shooter. Fundamentally, MWO has not changed at all since closed beta ... balance tweaks, some backend code, bug fixes, mechs and maps are about it.
However, it costs nothing unless you want to spend it and you don't have to spend it until the game is in a state where you might want to play it.
Overall, the vision of CW, and other features may give the fun 10 minute shooter version of MWO the metagame elements it has needed since closed beta in order to keep player interest in the longer term.
So .. why do folks threaten to leave? I don't think it has any impact on PGI ... they know exactly how well or poorly they are doing retaining players.
If you like the limited but fun 10 minute shooter then the game can basically only improve ... since it has NO metagame features at the moment and never has had them. (On the other hand, if they do manage to bollix up the introduction of these features, I too may consider the game a lost cause

However, other than the ridiculous amount of time that has passed and the pretty much incompetent time estimates for feature delivery that have been bandied about in the past ... MWO still has the core of a good game. All folks need to do is wait and see whether they can actually create the game ... and since it is free to play ... waiting costs us nothing.
If PGI actually wants the revenue that these "waiting" players could provide ... then they will listen and address the issues required to generate longer term interest in their players by creating solo and group metagame content to drive continued interest in playing the game (since I do not see the fundamental ... fun 10 minute rinse and repeat battle elements ever changing unless they introduce additional game modes).