"Lack of manpower" is not a valid excuse when it comes to Gnome/GTK. If you redesign your entire codebase every other year, break everyone's workflow you cannot cry about lack of manpower. Writing software is one of the most expensive human endeavors in the world right now and FOSS community treats it like they have unlimited supply of it. If you have limited supply of software engineers then you cannot afford to redesign your UI and you have to stick to your existing code.