Lots of people are in the same situation I've seen myself in... we like Tk a lot, but the look and feel is so outdated. We've looked around at all the other options (e.g. Java, PythonWin, GTK, etc.) and while they tend to be better looking, they've also all got major shortcomings too. The question then becomes, what to do?
Tk isn't that far away from being decent looking, and in fact a lot of people out there have made it look good. This can be done through the inclusion of a variety of non-core widgets, careful mucking with widget options, attention to spacing, etc. Rather than everyone reinventing the wheel, it made sense to try to focus some of that effort and energy so that everyone can benefit - by rolling those improvements into the core in some reasonable way.
We've opened up a ProjectForum site on tcl.projectforum.com for this, which Steve Landers and I will moderate for now. We think in the end trying to brush the dust off Tk will give a better result with less effort than investing in any of the other solutions out there.
We'll see how it goes...