Maybe there is an upside to MS mandating secure boot.
It means that Linux users cannot use MS-Windows-8 certified hardware, so instead of just grumbling about paying a "windows tax" they will be more motivated to petition vendors to provide MS-Windows-free systems.
Presumably a vendor could easily sell two versions on the one hardware, one with an MS-Windows sticker and secure boot enabled, one with no sticker (or maybe a "Your Freedom Respected" sticker) and secure boot disabled. They would just need a modest probability of sales to justify the small effort.
I'm sure we have the buying power to support vendors who agree to support our freedom, but as yet the motivation to use it hasn't been strong enough. Maybe secure-boot will change that.