What "actual hardware limitations"?  There are letters on a U.S. phone dial and have been nearly forever.   The bad UI was imposed to keep costs down and monopoly profits up.

True.  First of all, programmers only do UI because no one will pay for properly trained designers to do it.  And that, too, is a matter of keeping costs down and profits up.  If people wouldn't use bad UIs, the products wouldn't sell, but they *do* sell, so why shouldn't companies take advantage of that?