Hinges really aren't that great in that it limits the orientation of your top vent to one place only. Plus the 22.5 has tons of accessories that can be used, but not as easily with a hinged kettle. Plus it is a regular black kettle when they have made so many other interesting colors in recent history. The only real selling point is the charcoal ring and diffuser plate, but it really isn't worth the cost over one of the exclusive colors.
My advice would be to buy one of the exclusive colors on weber.com or grab a performer over the Master Touch Premium. If the diffuser plate and ring really interests you then invest in the Cajun Bandit Kettle conversion kit. It comes with a stacker, charcoal ring, and a diffuser plate. If you catch it on 10% off sales it is around $200 and will give you way more versatility then the MT premium ever would. I have one and it is a really nice set up for cooking direct with some height or smoking.
If you wanted similar functionality as the MT Premiums set up you could just buy the charcoal ring on Cajun Bandit for $45 and a large pizza pan to act as a diffuser on the cheap.