The -internal- Notes RichText should be able to convert to and from MIME with more coherence / fidelity.
Currently, MIME mails in read mode are OK (=HTML engine) but once edited or forwarded, they are converted in RT which result in something very different.
Even worse when performing MIME <-> RT operation on the backend (Notes Client using LS or on the server)
Most of today's content is unstructured, meaning RichText.
And most companies need to be able to exchange such information with other companies, with as much fidelity as possible, which cannot be made in 'Notes RichText' format today.