This is an add-on to (and a dependent of) Wallpapercraft - A Fresh Roll

Is this really necessary?

Maybe not. If the pack you are playing -- or planning -- already has some means of creating wall models from existing blocks, this add-on is largely superfluous. However, if migrating worlds from one Minecraft version to another is important, or another solution isn't available, then the add-on is a good choice.

If you don't want walls at all, then why are you even here? Beyond the clever description, of course.

Why not just add it all to the base mod?

Because alternate means (may) exist. Wallpapercraft offers significant variety. Because of that, it also means a significant number of models, recipes, and associated goodies. It seems appropriate to leave the addition of these goodies to the player or pack designer.

These are walls. Are there also stairs or slabs?

Stairs are available at Wallpapercraft - A Fresh Roll (Stairs!).

Slabs are available at Wallpapercraft - A Fresh Roll (Slabs!).

Dependencies

Wallpapercraft (Walls!) for Minecraft version 1.14.4 requires Wallpapercraft - A Fresh Roll version 1.0.7 or greater.

Wallpapercraft (Walls!) for Minecraft version 1.15.2 requires Wallpapercraft - A Fresh Roll version 1.2.4 or greater.

Wallpapercraft (Walls!) for Minecraft version 1.16.3 requires Wallpapercraft - A Fresh Roll version 1.4.5 or greater.

Wallpapercraft (Walls!) for Minecraft version 1.17.1 requires Wallpapercraft - A Fresh Roll version 1.5.1 or greater.

Wallpapercraft (Walls!) for Minecraft version 1.18.1 requires Wallpapercraft - A Fresh Roll version 1.6.0 or greater.

Wallpapercraft - A Fresh Roll (Walls!)