I am currently writing a simple-ish plugin with custom posts and a couple functions, using post metadata and adding a couple of variables to the "options" table in the database. During my research, I saw some references in the WP Codex about making the plugin backwards compatible with versions before WP 3.x and I was just wondering how important it is now to incorporate that compatibility.
For instance, the oldest version of WP I ever saw installed (by a client) was 3.2, or somewhere around there. I cannot imagine many people having anything older than 3.x but I could be wrong. I know in theory you should always try to make it perfectly compatible but, realistically, does anyone know how important it is to include that capability?