I'm somewhere in the middle between Boofo and TheLastSuperMan on this one.
Sure, there are a few very appreciative folks who will go out of their way to show their appreciation (at times even support with a donation).
But, the vast majority do not thank or even acknowledge the hard work done by the coders in the community. They just come on, download and leave. Heck, some people don't take the time to even click install and rate the mod. Sheesh.
I know that I ALWAYS click install, rate the mod and thank the person/company providing the free service. I've also been known to send a donation to the coders as well. But, I'm also the person that will take the time to post a fix and help others if it's something that I know the answer to when the mod is unsupported or the coder is not available at the time.
So yes, it should not be expected that everyone will do these things...but, they should be appreciative and support the coders by words, donations or assistance. Then again, this is not a perfect world, right?