I'm guessing font size regs are to prevent "RISK FREE INVESTMENT, (investment not risk free)" type things? That seems sensible. I can see there being rules for italics etc for similar reasons.
Wouldn't it be much less game-able to forbid LYING in a document, as understood by the elusive man-in-the-street?
Seriously: to judge a contract in case of a conflict, pick 12 people from the street and ask them to summarize it. Go with what they wrote. Going to "experts" when deciding language is what created the current mess, sticking to them is not going to solve it.
Most of time it isn't about lying, its about small print hidden in the document.
Legal text is often opaque to laymen because it has specific legal meaning, plain commonly understood language doesn't have specific meanings so you get into situations where even the lawyers aren't sure how it should be interpreted.
To use a tech analogy, the lawyerese is the source code, if you want the ultimate truth, go there, you should be pairing it with adequate documentation though.
