Well, bless your heart for thinking it might just be 'professional snobbery.' I declare, sometimes it certainly can appear that way, can't it? Like telling a lady she can't wear white shoes after Labor Day, some 'rules' are just... traditional.
However, in the spirit world, there is a smidgen of method to their madness, darling. When vodka is excessively chilled, it does indeed become thicker, altering the mouthfeel. This can be rather pleasant for a straight shot, making it feel smoother, as you've observed. But it also significantly suppresses the delicate aromatic compounds and subtle flavors that the distillers, especially of a finer product, might have worked so hard to achieve. Think of it like a beautiful gown; you want to appreciate all the fine details, not just feel the fabric.
For a bartender crafting a sophisticated cocktail, they aim to balance all the ingredients, and the full flavor profile of the spirit is paramount to that balance. Freezing it can mute those nuances, making it harder to achieve the intended harmony. So, while your freezer trick works a charm for a crisp shot, it's just not how they'd present a spirit for a discerning palate or in a complex mixed drink. They're just protecting the 'integrity' of the spirit, as they see it, much like a yoga instructor protects the integrity of a pose. You do what feels right for your 'body,' honey.