The elements are just big resistors, and their typical failure mode is to stop getting hot for a variety of reasons. Not much else can go wrong with them. By "too hot" do you mean that they are hotter than you've come to expect for a given setting, or that they are getting hotter than they've ever been? In either event the most likely culprit is the rheostat that changes the temperature as you turn the knob (if there are some kind of electronic controls then there are more possibilities). The likely cure is to replace the switches behind the knobs.

In answer to your question, swapping the elements will probably make no difference. Swapping the controllers might. If the burners are getting much hotter than they've ever been I'd definitely call a repair person, you could have bumped up voltage from a defective transformer for example-- I'd expect to see other problems in the house were that the case, extra bright incandescent light bulbs, etc. A bum controller is the most likely cause.