Microsoft benefits immensely from having programmers building things that run on Microsoft technology. It's the consequences of the tool use that are important, not the tool use itself. Adobe, conversely, doesn't gain anything from having images in the wild that were drawn by Adobe tools. Adobe is a tool company, so they charge for tools.
There's a good Joel Spolsky quote saying that the only reason Microsoft doesn't give its development tools away for free is to avoid accidentally cutting off the air to the 3rd party vendors who build and sell add-ons. There needs to be a little money changing hands in that space so that companies are used to spending money on tools, and therefore are willing to pay for things like ReSharper, Ants Profiler and CodeSmith.
There's a good Joel Spolsky quote saying that the only reason Microsoft doesn't give its development tools away for free is to avoid accidentally cutting off the air to the 3rd party vendors who build and sell add-ons. There needs to be a little money changing hands in that space so that companies are used to spending money on tools, and therefore are willing to pay for things like ReSharper, Ants Profiler and CodeSmith.