I understand what you are saying but to me it seems to apply to those who are doing more than shooting for the pleasure. Shooting for enjoyment to me is just that, getting out there and creating pictures because it's fun. I could care less if I ever make a penny from them and very few folks will ever see them. If I want a lens because it adds to my fun value, then I need it. I need no other justification.
So your answer to "Do I need another lens?" is "it adds to your fun value?"
My answer was: "Get another lens when you discover that your current lenses are blocking your artistic intentions."
Most of us in photography like it for its gadgetry. But if making good pictures is the primary intention, too much gadgetry can become an impediment to creativity. A picture can be missed while one is trying to change lenses, a good perspective can be lost because one has not fully explored the capabilities of a particular lens.