I cannot imagine why anyone would want their constants to look like variables?

Because variables Do What We Want without constant bletcherosity like the $foo{+BAR} hack? Which is buried way down in the bugs section of perldoc constant where nobody is going to see it, by the way. Seriously, someone ought to collect up all the "How do I do X with a constant?" FAQs and answer them right up at the top of the documentation.