A good example for why using closed source software (and thus depend on it) is a bad thing, can be seen in the newest development around X.org:
There is a new version of the X server, which contains ABI changes, and now all users of the closed source ATI and NVIDIA graphics drivers can’t upgrade to the newest X.org version, because those closed source software providers didn’t provide a new version of their drivers yet.
–> Avoid closed source software whenever you can.