Yes, porting apps to windows means a larger user base, but it often means a worse program. Windows imposes all kinds of stupid expectations that developers bow to. Witness backspace going to the previous page on all versions of Firefox. I have an example at my place of work about how we ended up having to implement our own timezone code because the windows timezone stuff is broken in various ways. Now our code has timezone bugs from time to time that affect all our platforms.
My expectation as a Linux user is that programs that are available on Windows as well will cater primarily to Windows users (the larger potential market), and will become less usable.