In the new Minecraft Update Announcement Mojang said they would be adding new Wool Stairs and Slabs. (And maybe walls?). My suggestion is to use this opportunity to further expand the Wool Block's palette by making it so you can use a Wool Block In a loom with each of the Pattern items.

My suggestion is limited to just the Pattern items to keep things simple but, if possible, it would be cool if you could customize them the way you can for banners with multiple layers and complex patterns. Though I understand that would require much more work to make possible hence the simpler suggestion shown in the photos.

EDIT:  
Id like to clarify that for as simple as this block concept may seem, such a block IS NOT EASY TO ADD TO THE GAME and can easily tank performance if added in poorly. You could add each version of the block as a block state for wool but that would require Mojang to make 2,560 blocks to account for all variants and put them in a poisiton to revist this block and add more later when new pattern items are added. They could alternatively do it like a banner but that requires them to be block entities which can be bad for performance, especially due to how many of these would be used in singular builds. Especially that brick variant.

So either Mojang makes new systems to better performance for this block, or make all 2,560 block textures/blockstates. This block wont be easy to add, but it has potential and would be an incredible block IF added.

SECOND EDIT:  
Due to people liking this post I will be making a YouTube Video that will go further in depth with this idea and give potential ways this could be added to the game. I will also show off potential build ideas as well as make a post on the offical Minecraft suggestion site. If anyone has further suggestions related to this idea please comment and ill see what I can do. Ill add the carpet designs that peope like as well. I will also begin work shortly after to turn this idea into a mod.

Woven Wool