Well, it may be "proprietary", but it is Open Source (IOW, it would be no more "proprietary" than Zope itself). I don't know too much about the MS api stuff - but you're correct that there's no reason better UI couldn't be accomplished with both. Our focus is mainly on Moz due to the Open Source factor.
And there's nothing wrong with that :-) The more the merrier.
With a web browser installation rate at approximately 70-30 it's impossible to ignore Microsoft, where one likes it or not.
Well, you certainly can't ignore if from the standpoint of making your Zope-created apps compatible with it. From the standpoint of making a better next-gen Zope management and app development interface though, IMHO browser marketshare or mindshare are not really that important.
We have a cross-browser mgmt interface now. What we want to get to is to have something better and more powerful as an alternative. If using the more powerful interface requires using a particular tool (no matter what it turns out to be), then our sense is that that is a reasonable trade off. Realistically, the core goal is a better UI, so any decisions like that will have to be based on merit and compatibility with Zope's business and technical goals, not market share. And as always, Zope is Open Source, so anyone who felt that we backed the wrong horse could always "correct" the situation :)
Yes, that's what ZIE is all about. Open one proprietary solution to Zope, as would any Dreamweaver et alt integration project would. Personally I would like to see a Open Standard based web content development scheme. WebDAV is a start for one. //johan