What I generally find puzzling is why so many of us want to graduate a.s.a.p. What is it that all these folks anticipate so impatiently that would happen upon graduation? I mean, does everyone who is in favor of graduating now realize what it'll be like? Ok, let me tell you what's my picture:
Many more basic, lower quality questions
Many more beginner users
Much less consistent voting (not only different questions / answers to them would receive relatively very different weights - which experts often would find inadequate, but also within the same question, truly great answers won't always win)
Much heavier load on all experts and advanced users to keep things under control, and most importantly, preserve the coherence of our community, the culture we've developed, etc.
To my mind, at any given time, we (as a community having experts, advanced users, intermediate users and beginners) can handle only so many basic questions, and beginner users who ask them. As we grow, we get more of the intermediate-level users who share our culture and are ready to take some of that load off the core of experts. We have now a great proportion / ratio of experts / advanced users / intermediate users / beginners, and I think this is one big reason why we are doing so well as a community. In other words, It is this power law with a much steeper power which makes us stand out (because it reflects an unusual number / proportion of experts willing to help). However, the other side of this is that, if you continue the curve to the other end, we have less room for beginner users than other communities (I mean the proportion, not the absolute number), at any given time (this room grows as we grow). This is a speculation on my side, but IMO power law is important, since it happens naturally in scale-free networks, which are characteristic descriptions for systems growing organically. Graduate now, and you will create a second exponent, with, I think, disastrous consequences for us.
Mathematica SE, as well as other similar SE sites, is a modern system of knowledge transfer (thanks to the SE team). We are attracted and willing to spend our time here because we see that this system is effective. It is effective because we have a coherent community with a certain culture, ways of doing things, informal rules, etc. But we are still very young as a community. Scaling this effectiveness to larger community size is a non-trivial task. For knowledge transfer to be effective at the larger scale, we need more intermediate users willing to participate and serving as a bridge between experts and more beginner users. It is not accidental that, while we are doing more than well in numbers of experts / advanced users, our number of intermediate users is just a fraction more than is requested. Besides that, we need also more questions already answered, more "canonical" / "generic" answers (which serve to prevent duplication of efforts and fragmentation of knowledge), more people who are aware of past questions and generally carry our common knowledge, etc.
To summarize, I have a very strong feeling that we are not yet ready for rapid expansion. All those parameters which SE team introduced to measure the degree of our readiness for graduation are there for a reason. Right now, I think that the longer we stay in Beta and accumulate critical mass (in many aspects), the better it would be for us (of course, I don't mean staying in Beta for years). We have previously happily existed on Stack Overflow for years, and, while there were certain problems and inconveniences due to restrictions of SO format and misunderstandings with users coming from other tags, I think we were doing great. Right now, we already accumulate new users at the rate unthinkable for the SO Mathematica tag, and have other signs of rapid but healthy growth.
So, what's the rush now? My two cents.
I highly recommend to read this blog post, coming from an SO user who was consistently within top 10-20 SO users for extended periods of time while still on SO.