Tarps!

Building with fabric is pretty awkward in Minecraft. Sure, there's carpet, but carpet can't be placed vertically, or even on stairs. Banners can help in some situations, but the idea of large sheets of fabric, e.g. sails, tent tarps, flags is hard to convey in Minecraft. Wool blocks seem to me like a placeholder system left over from the earliest days, to be replaced by something more elaborate later on.

The way tarps should work, is that the shape of the tarp block should be determined by the presence of tarp blocks surrounding it in 3 dimensions, like a combination of the behaviour of glass panes and rails, to combine into a continuous, thin, non-blocky (meaning lots of 135° angles, but no 90° ones) sheet.

There should be wool tarps in all the colors of course, as well as leather tarps, straw-, wicker- or bamboo weave, and nets, which would be transparent. Crafting recipes should be 2x2 wool blocks, leather, wheat, vines or bamboo, respectively, or 3x3 string for nets.