.Net Continuity of operation and re-use of code, until the next iteration is released and you have to refactor your old program. Again. Or god forbid you get situations where you need multiple versions of .net co-existing within the same system because dependency hell.
I know developing for the now on .net is pretty easy; and it's great for throwaway programs... But it is not a stable platform. The mind boggles at how much stuff expected to last years is coded in it, and inevitably runs into problems.
Not saying any other programming toolkit is much better, but there is something to be said for clean and minimal applications. I still have Fortran code from the 70's in a production environment, and I can always get it to run.
Whereas, .Net from 10 years ago, good luck even getting a working op system installed to take it unless you've filed away the relevant os patches in the right order.