yEd is seriously awesome, and I don't foresee ever not using it! But its functionality is falling behind the times. Neither the user base nor the product seem to growing as fast as it deserves. The lack of modern features hinders more widespread adoption.
yEd could hit several dozen feature requests with one stone if it empowered its most passionate users through an open source plugin architecture. Look at the popularity of Sketch by Bohemian Coding, or Sublime Text. Users who are passionate about the core program contribute plugins to the ecosystem, attracting even more users, in a virtuous cycle.
This very forum is evidence that there is enough passion for the product that users would contribute plugins to such an ecosystem. Let's have an open source plugin architecture. We're ready.