Amen. I wish there were a MobileSafari preference to ignore all the terrible viewport business (I am so fucking sick of websites with tiny type disabling my ability to zoom!) and send a desktop safari user-agent on top.
Even Motherfucking Website[1] cocks this one up and disables zooming.
Disabling the viewport on websites that need zoom is really bad design, but if you have a website that is optimized or at least scales well to mobile sizes then disabling zoom is better. If the user doesn't have a reason to zoom on to content then accidentally zooming makes for a worse experience.
Although I agree that there should be an option to disable the disabling of viewport zooming; I think it makes for a better UX for most mobile website viewers.
Even Motherfucking Website[1] cocks this one up and disables zooming.
[1] http://motherfuckingwebsite.com