Informally watching our stats on Area 51 leads me to the conclusion that our number of users and visits per day have increased faster than our questions per day. We use to be averaging a question per 100 visits and now we are averaging a question per 200 visits. I am concerned that we do not have enough questions to keep the interest of our new visitors. Should we as frequent users ask some general interest questions, by which I mean questions we had earlier in our careers and now know the answers to, to try and keep interest/visits high. Hopefully more questions would encourage new users to ask more questions.
Before we jump to conclusions, do we have statistics about the rate of question generation on "graduated" sites?
It may be that we're getting a lot more "casual users," who just want answers to a particular question. When they find it, they don't need to ask it, because it's already there.
That said, if there are a few "low-lying fruit" questions, then we could certainly encourage them to be asked! Not quite sure of the best way to go about doing this, but I'm open to suggestions.
“Seeding” can happen very naturally, by the regulars simply asking more questions. It is good to ask questions, even hypothetical, that come to your mind or come up during lunch discussions with colleagues or friends. Even if you think you have an answer, even if it doesn't apply to you, as long as it fits the site (not overly broad, not too localized, etc.). I regularly do it (in fact, more than 25% of my posts are questions), here and on other SE sites, just like I would ask a colleague at coffee (“hey, I was wondering about …, maybe you know the answer or have an idea on that”).
Organic growth is healthy. All the statistics I've seen indicate that's what Academia.SE is experiencing, so we shouldn't worry overmuch.
Stats aren't bad and, AFAIK, they are going up (from time to time I check them). The later is a think that SE admins care them most so I bet that we are not in danger. I really doubt if they care at all about views/question; but if there is a single parameter they want to be high, it's views :).
And personally, I think that the number of questions is not bad. Compare to other sites. Especially when subtracting piss-poor quality questions.
When it comes to seeding - why not? But it would rather generate more views, that (much) more questions :).
I would rather think about extending scope (e.g. also to a bit more localized questions).
If you look at some other far more popular beta sites, you'll see our question rate is pretty typical. Without having access to the stats, do note that as we get more popular (and as more questions are asked), more people will arrive here from google search results, see their answer, and then leave. That's not necessarily a bad thing at all. Hopefully they'll stay in the longer term, but I wouldn't be too worried.
This is a good time to put in another plug for advertising, though. If you're in a university, post flyers, tell students to use the site, ask the administration to send students here, install rootkits on students research computers to send them here instead of google, whatever works to generate more traffic.
To answer your question Why aren't more questions being asked?
Obviously, people in the community around the Academia beta site rather think twice then ask a question that maybe down-voted or closed for some reason (too localize, too broad, off-topic, duplicate...). As eykanal and Piotr Migdal mentioned, it is typical for beta sites. The community around beta sites are more interested in the forum and StockExchange in general comparing to majority of non-beta sites visitors. "Beta" users will probably become users with +200 (500,1000,...) reputation in the future. These people generate content of higher quality but as we all know, it is very difficult to have both quality and quantity.
On the other hand, if you take a look at normal sites (non-beta), you can see very often people with 1 point of reputation, several times per day. These people are new (as I was once) and most likely did not know about StockExchange before. They do not care much about the community, they want they questions answered. Of course, their questions do not have high number of votes and are often closed, but, there is nothing wrong with that(!!). (this is a very nice discussion tree regarding duplicate question in stackoverflow; Academia will not suffer that much because there will be no question about programming and stuff.) (one interesting from AL&U meta about a lot of closed and down-vote questions)
What I am trying to say is that if the Academia site is going to become a non-beta, sooner or later it is going to happened and we should not be surprised. Users are here to ask (and answer) and core users to moderate, to make the content as much valuable for others as possible.
With a little bit of humour we can say: When there will be more questions? When you will see a lot of them closed :D