Agreed. How does tearing someone else down make the OP or any of us better magicians?
In a few ways.
1. When someone (eg Brian Tudor, me, or you) puts their image and ideas into a creative work and sells it, they are tacitly offering said content for review and criticism. Every single bit of criticism, whether justified or not, constructive or not, represents a human being's reaction to your work, and is therefore useful to a performer who wishes to control audience response. The performer can analyse the critique, abuse, or praise to ascertain exactly what elements of the presentation elicited the response, enabling future output to be honed.
2. Taking the role of devil's advocate, adopting a deliberately contrary position, fuels debate and can serve to shake people out of a complacent, unthinking point of view. In other words, when you've settled into a rut of responding with a standard-issue, knee-jerk reaction on a given subject, hearing an alternative, extreme take on that issue should inspire you to examine your own motivation and study your own logic. This way, you can assess whether your views are based on rationality or comfort. This is useful for us as people, and, when the subject relates to magic, us as magicians.
3. It's a good way to get publicity. The "angry" presentation worked for Brian Tudor, as that clip is endlessly shared and posted around the internet, and "ranting" may work for Michael too if he really hits a nerve. You could argue that getting publicity doesn't make you a better magician, but it gets you a bigger audience, and therefore more people to critique you, which, ultimately, does help you become a better magician.