I totally agree, who cares?, except if Sigma is that great that people will want to see it, and know what that means, the Sigma logo, then they should be demanding that the logo be placed.
In fact the company is worth so little in market cap, that if a manufacturer truly wanted the Sigma product, surely they would just buy out the company, if the scale was a hundred, thousands of machines.
Put another way what is Sigma's leverage to demand a premium?, and to place the logo?
Ideally everyone will want to see the Sigma logo on the machine, but they don't.
GL