I mean, you're not wrong. Open is a strange spell. Rather than have it act as a touch spell as both the name and description suggest, classic casts something on the player that alters his next attempt to open something. So you can cast it, walk around for 5 minutes, and then open a locked door. There is no status icon that shows up to suggest you are imbued with magic, and the duration given in the spell maker vs your spellbook is totally different.
The message "Ready to open" doesn't exist in classic and is Interkarma's attempt to make the spell less confusing, but it accidentally made it equally confusing since people are reading it as "(door is) ready to open (because I just unlocked it)". It's okay IK, I feel your pain