"Boutique" is being applied to festivals attended by numbers from 500 to 50,000. So what does it mean?
1. a small shop or a small specialty department within a larger store, esp. one that sells fashionable clothes and accessories or a special selection of other merchandise.
2. any small, exclusive business offering customized service: Our advertising is handled by a new Madison Avenue boutique.
3. Informal. a small business, department, etc., specializing in one aspect of a larger industry: one of Wall Street's leading research boutiques.
4. of, designating, or characteristic of a small, exclusive producer or business: one of California's best boutique wineries.
As you can see, it means either "small" or "exclusive" or "customised". But "exclusive" or "customised" cannot be applied to any festival, as tickets are on sale to the general public, and attendees cannot customise the festival. So it means "small". Yet when "boutique is applied to festival of all size, it ceases to have any meaning, and just becomes marketing blurb - meaningless marketing blurb.
If a festival is having to rely on mis-using a word to try and get the punters in, what does that say about that festival? At best it says nothing at all - after all, thru mis-use of the word its meaningless in the festivals marketplace - but at worst it says far more and nothing good.
It says that a festival rates meaningless words above substance; it means that that festival will say anything to try and get the punters in, when their efforts would be better spent putting on something to get the punters in; it says that it's very likely that the festival is going to deliver something short of what you might hope.
In a world full of shit and a music world full of hype it's always best to keep it real.