Absolutely. I do this all the time, but it's a lot of stuff and my time is limited. Also, manufacturer lock :)
True, but so is everybody else's, including the people who mod the site. This is a community effort, we all pitch in somewhat.
[...] I wonder if a broader category like "Modulation" with sub feature filters that one could select multiple feature from would work? For example the user could select the FUNCTION Modulation and then select 1 or more multiple FEATURES like Attenuator, Envelope Generator, Mixer.
I am not sure adding a multifuntional tag would solve the problem. Though the idea is right in that broader categories to encapsulate modules main function might be beneficial. This is provided more detailed sub-tagging could be applied and the method for searches allowed one to select multiple features. It could mimc ecommerce product listing page filters. For example, if one is looking at a product listing page for the t-shirts category then could then select the colors black, red and blue from a filter list and not have to see white, yellow and orange.
I think you're simplifying the problem to a degree which is not realistic. Color is an attribute and can easily be defines as a subgroup of a product category. It is a rather obvious one and makes for an easy UX choice, whereas functionality VS features are interchangeable attributes. To extend your example, where does Mixing fit in terms of Utility? Is it a subcategory of Utility or a different function entirely? This is all subjective as we try to define usage in an area which by definition tries to avoid it. Modulation, right, what about all the oscillators that can go to LFO speeds? It's a can of worms.
Again, in my most humble opinion, the problem we're facing is having too many disparate modules on the grid. If we get the option to merge, categorize as one-off creations or manufactured (because not all manufacturers are properly listed) and then allow for a maximum of 3 tags per module, that could make things far more easier to navigate. What if a module can do more than those three things? Well, you know what, that's what manuals and demo videos are for. We also have a huge database of info on MW FB and MW forum and that's what the internet is here for.
Personally I don't have much of a problem with the tagging system as it is; I don't even mind being able to give all the tags for all I care. I would only make the question more apparent when someone uploads a module "Can it provide this functionality to other modules?" and have the uploader tag the module as such. It's easier for users to have to answer a question than not, it helps to focus. But you raise a fair point as we do see tags being misused.