When reading this, two words jump out at me as missing: consultation, and simplicity.
Consultation as that's something that has always caused problems in the past: changes being made without adequate consultation ahead of time, or even plans being made without adequate consultation. That's a bit different from collaboration, which comes after consultation (and is good to see mentioned in its own right).
Simplicity is probably a bit more controversial, particularly within Wikimedia as we end up catering for every viewpoint rather than trying to focus on what's essential. Hence even the name 'Wikimedia' (and all of the other names things in the Wikimedia movement go by), while 'Wikipedia' is the brand that everyone knows. And hence big lists of links in sidebars, as another example. But simplicity in both form and function is quite important to make things user-friendly.
I hope those suggestions help. :-)