Thing is, after the next update, we'll have wool, hardened clay, and concrete all at the same time, and I think this is a good opportunity to have bordered (polished, in other mods) decorative blocks as a default. I can't remember what the pack defaults are for these blocks, but I'm currently using patterned grid wool and "cracked" hardened clay, and given that clay generates naturally in mesas, perhaps that should be the smooth decorative block instead?
In addition, for those using smooth wool for decorative/creative building purposes, having another smooth block type would be a bit redundant.
EDIT: I've played around with Dwarven as well and noticed that hardened clay is a polished/bordered variant. It definitely looks great as a decorative block, but not so much as a naturally generated clay in biomes. Then it just looks really odd. Perhaps concrete would better fit this role as it's a totally player-made block.