Like to chime in here with a few thoughts. Considering that EE add-on development has exploded over the last year or so and that it probably will increase once 2.0 is out, I find the official repository quite necessary in the future. I must admit that I seldom use it, but if I do expect the add-on to work.
And I also expect, and hope, the repository won’t include all those add-ons that aren’t really necessary. One of the most difficult things about add-ons is to sift out not only those that aren’t robust enough but also those that do not add any functionality to EE. This goes especially for the commercial ones we see more and more of.
Devot:ee is great but no matter how many favs, rankings etc an add-on has, there is no knowing if it will work in the specific set-up I’m using or in the specific environment I’m developing in. Don’t know how many times I’ve installed add-ons, fought with them, only to discard them, and many of them are highly ranked in the community or at devot:ee. Rumor, enthusiasm and good will has a tendency to spiral…
Still I check out Devot:ee, I usually know which devs to trust, I keep a blind eye to the rankings, but how will it be in years’ time? How many add-ons will there be by then? The official repository can help me to narrow down my choices to vetted add-ons. But will EllisLab have time for vetting and quality checking as development speeds up? I do hope we won’t end up in that wild WordPress jungle of plug-ins that may be maintained or not, that may be compatible or not, that may, may, may…