Special events like the Commonwealth Games aren't focused on traditional tourism in the same way they're not focused on legacy infrastructure (although they certainly can benefit both).
Special events are televised.
Exposing the City to a potential audience of 60 million people (the estimated number of people who watched the '94 Victoria Games on TV) has a benefit that extends far beyond tourists popping into town for a few days, and walking around the Inner Harbour and up 7 blocks of Government Street.
There's nothing wrong with a music festival, indeed I've participated in many of them. But when the reference is to a "Special Event" like the Commonwealth or Olympic Games, the "Special" has a defined meaning that extends far beyond anything related to local or regional music, dance, or theater.
EXPO86 and the Winter Olympics fundamentally changed Vancouver in the eyes of the rest of the world. It also fundamentally changed how residents viewed their own city.
For better or worse (which is totally subjective), Special Events like the Commonwealth Games permanently alter (by design) the locations in which they occur.
My experience on numerous Special Events, and specifically the Commonwealth Games '94 edition - was that these types of events inspire a specific mindset.
You either have a positive mindset like the thousands of Games volunteers, the 30+ thousand folks at the Opening and Closing Ceremonies, the tens of thousands at the Inner Harbour concerts that enjoyed the "94 Games, or the 10's of thousands who attended the sporting events themselves ... or you have a negative mindset that focuses on the cost to host the Games, where the money could be better spent elsewhere, and things like increased traffic and expensive tickets.
Either viewpoint is totally "OK" in my opinion, because it's all subjective, and it's all personal.
My point is that there is a defined purpose and deep reasoning to the concept of hosting Special Events ... that's why cities, provinces, states, and countries choose to host them in the first place.
Special Events also inspire somewhat rabid positioning, both for and against ... that's also part and parcel of the Special Events package.