I think its more a function of the fact that most implementations of wallets are designed to work across both Linux/Mac and Windows. If you've ever tried to develop for all three platforms simultaneously you very quickly realise that the GUI toolkits aren't very good. The best one is Qt (the same gui as the KDE desktop I believe) but it isn't as developed as many of the native GUI toolkits because it has to work across all platforms so is only as good as the most basic platforms.

When you consider that you wouldn't even have these frameworks if it weren't for open source then you'll realise its not actually a curse