You're correct about the worm in mezcal being a promotional device. However, I wonder if something that is dreamed up as a way to hype a product can become so pervasive that it starts to enter, and become part of, the popular culture.
You have a point. Each of us can probably point to things drawn up as marketing gimmicks that become widely accepted and expected. In some isolated instances, this may be happening with mezcal.
What I've read on the topic calls the worm nothing more than an advertising gimmick. Actually, it's not a worm - I read that it's a butterfly larva. Some critics of the worm say only bottles of poor quality mezcal contain it, to mask an otherwise bad taste. Although I drink it on occasion, I don't really like the taste of mezcal; I'm not about to conduct a taste test to see if the critics have a valid point.
Mezcal is becoming more popular in Mexico because of the inconsistent supply/availability of tequila and wide fluctuations in its retail pricing. I've no doubt we'll see an increased marketing and presence of mezcal in the USA because there's a larger mark-up on the product (as compared to tequila), there's a greater supply of the product and the USA audience doesn't know what it's drinking much of the time.
The vast majority of tequila is exported to and consumed in the USA and the Mexican spirits industry needs a replacement to quench the thirst of their national market. The result has been a marketing campaign in Mexico extolling the virtues of mezcal - as an "affordable" alternative to tequila. I've seen no ads/references to the "worm" in a bottle (in Mexico), and I think that gimmick is almost entirely rejected by Mexicans. However, for foreigners/tourists, it draws attention to the few bottlers who use it and, as we know, gimmicks often help to sell a product (quality be damned).
In addition to larva in bottles of mezcal, there are artificially flavored mezcal's - gran manier, lime, vanilla, chocolate, etc. They're produced for and marketed to, almost exclusively, the huge number of tourists clogging the streets of the city of Oaxaca. Most of my Mexican friends chuckle when they see someone buy this stuff - they wonder if we're all fools.
I thought that if we were striving to have as Oaxacan-representative meal as we possibly could, a taste of mezcal was appropriate. Mezcal without the worm!
Thanks for your follow-up comments.
To learn more about the "worm", mezcal and tequila, follow these links:
History of the Worm
http://www.mezcal.com/worms.html
All You Ever Wanted to Know About Mezcal
http://www.ianchadwick.com/tequila/mezcal.html
Tequila - Culture and Myths
http://www.ianchadwick.com/tequila/tequila_index.html