what a great idea, thank you very much. Two years ago I was evaluating different signing solutions for the company I worked with and there were two killer features that forced us to go with docusign since at the time they were the only ones really supporting it:
1. Relaying of Submissions to other Signers
We often found that we needed to get a Signature from someone at another company. However, we couldn't a priori say "Person X has to sign it". Often we had a contact person that would help us navigate the internal structure of the other company and relay the signing to that person. Docusign has the ability to allow us to say this person we know can decide who has to sign this document, even if we don't know that person. No one else at the time supported that use case.
2. Qualified Electronic Signatures
So... Here in Germany our Government has some kind of Angst (might call it german angst) of anything digital. A Handwritten signature on a piece of paper is held in such high regards that the digital equivalent (qualified electronic signatures) require a video ident workflow with a passport held into the camera and so on. This has to be done via a third party service that takes like 15-20 Euro per validation. I know it's insane. There's a reason that theres no german silicon valley... Anyway, there are many situations where this level of validation is required by law.
Just my 2cts after dealing with this issue here, I think 1. is something you might look into implementing, cause it's a use case that might come up more often, 2. is just really annoying for everyone.