Musical Comedy Theatre is primarily useful if there is something on during your stay. It gives Tashkent another evening option and can be a good way to see local cultural life beyond the standard daytime sights. It is a little away from the tight centre, but still close enough to fold into a half-day plan if the subject interests you.
Check the programme, language, and ticket rules before going. Even if you do not attend a performance, the building and its immediate surroundings may be worth a brief look if you are already nearby, but the real reason to come is the calendar.