Some good reasons to prepare new beds in fall

I wasn't organized enough to prepare the garden beds last fall. Or, maybe organization wasn't my problem and time was. Either way, I'm playing catch up now and trying to get some beds done up in time for planting (especially since I've got dozens of plants on the go in the pink bathroom that will need somewhere to live pretty soon).
I've built a few raised beds already (old cinder blocks supporting frames I made out of 2x4's) and have lined them with screening in an effort to keep the mice out of the beds as much as possible. There are more beds to make, though, and then the filling. I didn't think it would matter that I started in spring, but there are a lot of drawbacks:
1) The weather. Of course the weather.... it is often too cold or too windy or too rainy to do much effectively.
2) Materials. As of yesterday, I still have not been able to get bulk soil trucked in - the deliveries don't come in for a week or more. And those plastic bags of 3 in 1 (which would bankrupt me if I used them in place of a truck load) contain soil that is still partially frozen. There is supposedly an abundance of manure available, but I haven't found many farms selling it yet.
3) Time. Getting the beds ready takes time away from all of the other spring duties that are begging to be done, now that the temperature has suddenly jumped from barely above zero to high teens. The stones to rack off the lawn (courtesy of the plowing), pruning the lilac bushes, fertilizing the shrubs... it all needs time, too.
4) Ambition. The soil needs to warm up sufficiently before I plant all the tomatoes & peppers I've started, or the beans I've selected. This means that the time I'm spending on building the beds could have been devoted to building cold frames and the time delay in getting soil and manure could have been better spent with the prepared bed under plastic to warm it up.
5) Soil health. If I had done all of this last fall, the worms and soil organisms would have had all winter to enjoy the ammendments, and to start colonizing the new layers.

But it is what it is and I've learned my lesson. Should we decide to expand our garden dramatically, I'll start in September or something - or at least today I imagine I will, but no doubt I will run out of time and end up doing the same thing over again.