It's little surprise that so many of the few long-running anthology programs of the past thirty years have been based on pre-sold properties (Friday the 13th, Twilight Zone, Outer Limits) or recognizable brands (the feature film horror directors brought on to make Masters of Horror).
You're right about the cost, that seems to me to be the major objection. But Star Trek is
a highly recognisable brand, isn't it? It doesn't seem like your last paragraph works as an actual objection to the idea of a Trek anthology series.