It would be nice if for plans that can only had a dedicated IP the IP manager would not show buy more IPs or assigned IPs. This might confuse customers when they already have the only IP available.
Ideally it would ask to buy a new IP if a dedicated IP is not already purchased. And be removed once added or an option to remove dedicated IP only.
This could be tricky because some hosts include reseller privileges in their hosting plans so it would be o.k. for them. I would think it would have to be a box to select next to certain plans.
Reseller, VPS, and dedicated servers are correct with how it is now of course.
But plans that just allow for a dedicated IP would benefit greatly from being changed.