There is no way to define description for the plan. So there is no way to stick to the DRY principle when working with plans. New field long enough to put JSON data in it will be fine.
Thank you for submitting your request Igor. We've added this request to our feature list and we will give you an update when we take this up for implementation. There is no ETA for this feature at this moment.
Please, add merge for plan description. It will be usefull on account page too.
Yul, are you referring to the plan description in the customer portal? If so, we would add this as a feature request, thank you.