A great many restaurants list a single vegetarian main course, and it is frequently the least interesting item on the menu. The pattern follows from how kitchen resources are allocated rather than from indifference.
Every item consumes station capacity
A line cook works within a fixed set of wells, pans and refrigerated drawers, and each dish claims some of that space permanently during service.
A dish selling in low volume occupies the same footprint as one selling constantly, so the space it takes is measured against what a better-selling item would return.
That calculation is why a second vegetarian option often loses to a third variation of a popular protein, regardless of what anyone thinks of it.
Low-volume items create disproportionate waste
Components prepped daily have a shelf life, and anything left at the end of service is either used tomorrow at reduced quality or discarded.
A dish selling a handful of portions a night forces the kitchen to prep a minimum quantity that regularly exceeds demand.
Kitchens respond by building the vegetarian dish from components already used elsewhere, which constrains what it can be before anyone considers the cooking.
The dish carries a group, not an individual
Restaurant reservations are usually made for tables rather than diners, and one person who cannot eat anything on a menu can move the whole booking.
A single adequate vegetarian option is enough to prevent that, which means it is often designed to be acceptable rather than to be chosen enthusiastically.
This explains the persistence of the safe risotto or pasta: it fails nobody, and failing nobody is the specification it was written to.
Margin works in the opposite direction to expectation
Vegetable ingredients cost less than most proteins, so a vegetarian dish can carry a strong margin if it sells.
But vegetables demand far more prep labour per portion, since they need peeling, trimming and individual cooking, and labour is the harder cost to control.
A kitchen that invests that labour and then sells few portions loses on both sides, which is why the economics only work once demand is proven.
Restaurants built the other way round behave differently
Kitchens with a vegetable-led menu prep vegetables at volume, so their per-portion labour falls and their variety rises for the same reason a steakhouse can offer many cuts.
Cuisines with a long vegetarian tradition show the same effect, since their vegetable dishes are core inventory rather than an accommodation.
The single dull option is not a statement about vegetables. It is what happens when a vegetarian dish is the exception in a kitchen organised around something else.