I agree with 'de_watcher that FOSS/encumbered is an orthogonal axis to complexity/simplicity.
Lots of FOSS software is excessively complex (the systemd ecosystem of shovelware comes immediately to mind) and lots of FOSS is simple. Similarly there are untold thousands of overcomplicated/overengineered proprietary suites and of course it's hard for a graphical application to get simpler than notepad.exe.
Really? In my experience, FOSS tends to be a lot simpler and more streamlined than non-free software with comparable functionality.