I've been following this list off & on since January of 2003, maybe longer than anyone else here. (I can think of 2 or 3 who have subscribed for at least as long, & they are welcome to contradict the following; they are probably right.) I believe the change in this mailing list is simple: it's no longer as important as it used to be.
When I joined in that January, there was no Signpost, no WP:AN or WP:AN/I, no ArbCom. There was the Village Pump, but if I remember correctly, it was used more to answer newbie questions than to discuss anything. In short, if you wanted to know what was happening on en.wikipedia, you subscribed to this mailing list; it was the center of our little village back then. And not only could you exchange email with Jimbo & the other influential folks in Wikipedia, you got to read about the latest whining of troublemakers, rants by unreasonable editors, rambling tracts from kooks. There was good & there was bad.
Then the village named Wikipedia became a city. WikiEN-l gradually became a backwater.
In many ways, the threads in this mailing list are like the conversations of old men in a once important club, where the elite met to make deals & decide important issues: there is a lot of wisdom drawn from experience here, but also a lot of talk for the sake of talk. In the last few months it's gotten to the point where many threads follow the same path: someone bursts in about some outrage, a change that's going to ruin Wikipedia irrepairably. A number of voices chime in agreement for a period, each trying to outdo the other. Then comes a second wave of voices, arguing the opposite opinion. Sometimes a flame war erupts; sometimes some useful insight is offered. In either case, the thread always ends in time for the next announcement that Wikipedia is about to be ruined irrepairably, & the cycle repeats.
Meanwhile, the important work, the important decisions, they are all done elsewhere. Troublemakers are found out & handled. Policy is created & changed. Problems are identified and, in the slow fashion of the Wiki way, dealt with. I wouldn't be surprised if many Admins are unaware of this mailing list, let alone know what is being discussed here.
I don't mean for this to be an argument for ending this mailing list; I think it still has much value, & is at least as useful a forum as any on Wikipedia. However, the next time someone feels she/he *must* argue some point to the death, remember that this mailing list's influence doesn't extend much further than the few hundreds who read it, not all of whom are active participants in en.wikipedia.
Geoff