My experience is that development of features on the desktop version is continuing, but restricted mostly to bug fixes and stability improvements rather than major updates at the moment. There has been more focus on getting the feature sets of iOS and Android versions up to (and in some cases surpassing) the Windows version. If you want to promote an idea for a feature, it needs to have widespread support rather than being a niche idea. It's also a good idea to get beta testers to support your idea, as they can discuss and promote it on the beta forum as well. UserVoice does get reviewed, I think, but it has some inherent flaws which mean that there's a benefit to discussing the best ideas on the Google Groups.
Stéphane