There is nothing wrong. Before, you only had to care about your app running on a VGA monitor. Now, you have the possibility to make it run on devices of all sizes, resolutions and shapes.
Not really. Most productivity software still runs on desktops. We sacrifice too much to the Resize Gods without actually using them. It's like costly shrubbery insurance. (YAGNI.) Desktop GUI's were both easier to specify and were more productive to use. The "responsive" designs waste screen real-estate and require more steps to do the same thing, on average. The labor math usually says "no". There may be a subset of features that phone users need, but one can make a separate sub-app for those rather than poison the whole thing with mobile-oriented drawbacks.
