You are losing creativity, flavor, role play and character customization and for no legitimate gaming reason that I can see or that you have offered.What I'm saying is one, the way it is written, and two hardly more limiting than yours. So what if all you can do is sub any energy type for any other energy type. You can still get around almost any resistance that way. All you're losing is cheesing in a slashing damage fireball. Hell, you aren't even losing bludgeoning or piercing damage.
That and their intentional use of the word "appears" is why I am confident my interpretation is correct.