My two cents: SmartFit and Fit to Width have been done for years by Access's Netfront browser, which, to me, provides the greatest amount of control over how content is displayed, of any mobile browser I've used. I can tell it whether to include graphics or not, whether to display just the text without any page layout formatting or display it with page layout formatting, turn on or off a virtual window, etc.

With NetFront I can view written content pages without distracting ads or images, and they load ultra-fast over cellphone networks. But more importantly, the text wraps and flows over a single screen without ruining the entire page.

Such features would be highly desirable in Fremantle. I agree with the OP and several commenters that horizontal scrolling is undesirable.

User-specified CSS files may be a way to mitigate the problem, but only if Fremantle respects CSS specifications with regard to text flow, font sizes, etc. (I haven't tried it yet).

Then again, there's always Lynx...