Field Formatter "Summary" for "Text With Summary" fields

Problem/Motivation

There is a reason why the fields type "Text With Summary" haven't a field formatter "Summary" ?
I can set just 3 differents formats :
- Default
- Summary or Trimmed
- Trimmed

I want just display the summary when it is not empty and if it's empty, i don't want display anything.

Solution
It's a good solution to create a new field formatter "Summary" ?

Thanks for your help!