Making the "Product" dropdown non-mandatory enables people to submit ideas for NEW products or for products not listed.
The only workaround I can find so far is to create a Product called "New Product" or "Unlisted" and for the user to select that instead.
Thank you for your idea. Currently ideas must be associated with a product because ideas live within specific products. As you noted, one workaround is to add a general product where portal users could add ideas. You could also create a central "Intake" product and route all ideas to that product, then distributed them to the correct product when reviewing new ideas.
At this time, given the options above and current priorities, we are unlikely to implement this idea. We hope you can understand.