Friends who grow tomato plants under cover north of Seattle cut the bottom leaves off soon after planting in order to interfere with one of the blight problems they are prone to here. They may look ridiculously over-pruned at first but they say they develop well anyway.

That sounds like a good idea.... I'll cut them off the affected plant and keep an eye on the other to see what develops (other than tomatoes, of course!)

Fine Gardening has an online piece on tomatoes, and the author recommends pruning all the branches below the first flowers, as soon as the first flowers appear. I have two tomato plants in containers on the deck, and I tried this with one of them and not the other. Same species, same age, etc. The one I pruned per FG instructions is doing much much better. No spotty, curled, or yellow leaves. And many tomatoes as compared to only a few on the other one. These are Roma tomatoes.

Branches, or leaves? Pruning the branches is to grow the plant as a single-stemmed vine. Cutting off lowest leaves is for disease prevention.

I've just been taking off the leaves, as I want a bushy plant.... my pots are too wobbly to hold a tall vine. They seem to be thriving, anyway!