Alternative is a dress code, which I have 'qualms' with. Especially when you can meet it word for word, but an organizer still has the liberty to say, 'wear something else' - that is but the smallest 'qualm' of an enormous list I am far too lazy to write out.
I don't think jerseys are such a bad idea when it comes to building a brand, whether it's a bigger umbrella like MR, or a smaller brand like the tournament itself. Let alone the potential for generating revenue through sponsors etc.
MR are linked with Onboard, which is a buddy of one of their stalwarts, there's money for them to be made off these jerseys. The price difference between what a company like Onboard sell jerseys for, and the actuality of manufacturing costs... BIG. But yeah, you're right, MR higher ups for sure have deals, plans and numbers to crunch.
Like I said, I agree with you about a polo being enough. Tournament gave me a nice one, I would wear it.