I wonder if they considered involving both sides of the contract from the get go. When I've negotiated small-mid size deals with other tech savvy folks, I've often thought a two sided chat style interface that I could use sitting next to someone or if they were across town would be ideal.
The way I conceptualized it would be a 3rd party tool for making deals where the main feature is standardized clauses for minimal lawyer involvement. Eg. Need a standard confidentiality clause? (Drag Drop). Boom. Let's do business.
Commercial lawyers would hate it, but that's sort of the point.
I think the primary issue is that when you start redlining, everyone has their workflow and the side that's in the "position of power" will use what they feel like using.
"Oh check out this contract at FooBarContracts"
(counterparty opens link, copies text into word doc, edits)
It could be an iterative process, with niche domain and custom clause support. For small-mid business people interested in GTD, I think there would be enough utility gained by both sides to remain on the platform. For experienced business people, involving the lawyers is an inevitable drag on dealmaking.
I bet people involved in frontline sales for (eg. software) would love something like this to exist for fast closes. There are your shadow unpaid product evangelists.
You're assuming both sides 1) play nice and 2) actually collaborate in that way. A lot of the time it is David (small corp) vs Goliath (huge corp) where David has to accept terms of Goliath on their standard deals or risk not completing the deal.
As far as tools go, ethnography can be very powerful in the right hands.