The automated, unlimited buying of produce pretty much eliminates the need for a garden, especially since vendors are so easily-accessible. Because money is VERY easy to come by in Glitch, and because produce is unbelievably cheap, gardening just becomes a more time-consuming, labor-consuming, and harder-to-access (you can only have one garden) method of getting produce. The reason we don't sell eggs, butterfly milk, and bubbles, too, is because it ruins that aspect of gameplay, in the same way that selling produce ruins the gardening aspect.
Removing produce vendors, while annoying initially, would promote trading between players who forgot a certain type of produce in their garden, adding to the vague economy of Glitch and boosting social interactions.