People love to say this, until others actually take that advice and NEVER come back.
Examples? Almost every single MMO for the past decade.
I play one day a week now, is that worth 20 bucks a month? I dunno about that.
Anybody who complains about a lack of content has to be in the extreme minority. I could imagine that 5% tops feels the same way as you do. Why would SE sacrifice quality to rush out more content for a small group of people who are just going to dedicate their lives to grind it out within a week? You're paying $10 to $15 a month. I'm not really sure what you are expecting to get? That doesn't even net my wife and I a beer and a glass of wine these days.
That's kind of the point of the gaming industry and why it crashed early on - The dev created content didn't hook people and keep people. I'm pretty sure none of us around at the time did our own creative gameplay for ET. MMORPGs at least before it became mainstream were always about the content the developers created and doing it with friends - The fallacy of current game design is we have to make the game entertaining or buy every aspect of the game after the initial purchase.
So most MMOs that failed in the past couple of years with lack of content being one of the reasons failed only because of a handful of people? ARR has absolutely no hope then.
Until you beat Twintania you're not done. Get to it.
I'd say the reason most MMO's have failed lately is because they have been pushing hard to target a wider audience. SWTOR targeted more than just the MMO audience and an MMO is obviously not for everyone. Additionally, there has been a lack of innovation in the genre as well. When you look at where the average level is for FFXIV (I'd imagine it's level 30 by now) you should know that it's not lack of content driving players away. It's lack of quality and innovation.