Honestly, I don't get the complaints (you're not alone) and I don't think I ever will.
Metro is fine, even great as a tablet interface. My desktop is not a tablet. Plenty of concise, lucid explanations are out there for the most common complaints, so there's really no point in my rehashing them here. Frankly I don't see what the big deal is with leaving in an option to disable Metro in much the same way that one "uninstalls" IE or WMC.