Flash has problems way beyond not being "open" software. A Flash application becomes a black hole of content. Stuff can go inside and animate, perform actions, and so on, but nothing comes out. A flash application has to make do with very cumbersome metheods to hook up any internal elements to outsitde elements such as the browser DOM or other flash applications on the same page..
And then, generating the Flash content is an exercise in patience since the interfaces are hostile and limiting in the extreme. It is still based on a very dysfunctional timeline-based animation metaphor, where as new tools such as SVG and Silverlight are not. While Sliverlight may also be proprietary software, it has external interfaces that can be used by a wide range of external objects and code, making it far, far more flexible. Silverlight can be designed in a modern object-oriented way. It was written for programmers, unlike Flash which appears to be built for graphic designers, with programming metaphors just tacked on.
While an open standard SVG has the problem that Adobe has abandoned it, and Microsoft has moved onto Silverlight because they wanted to add a more robust programming model, So SVG doesn't run consistently on any modern browsers, and unlike SIlverlight it is a display / animation language, and nothing more. Any SVG application functionality has to be provided by external scripting, which is still better than Flash, since you can use browser Javascript and you have full access to all of the objects inside a SVG graphic rather than the buggy, slow ActionScript used by Flash.
So there are no really great solutions yet. Silverlight is robust and flexible, and modern with really elegant programming metaphors, but proprietary and not quite ready yet. Flash is proprietary, poorly conceived, closed, yet ubiquitous, and SVG is open, very easy to work with, but not implemented very widely and reliably on modern browsers.
So we still are waiting for a decent web graphical interface. HTML ain't it. My bet is on Silverlight even though it isn't open, it just blows the others away with capability. The programmers that get over religious objections to closed software are going to find it a rich and productive environment for robust distributed applications.