@comprehensible Your question, Is the word Theory semantically too vague for modern technical use? is the subject of the first chapter of Richard Dawkins's The Greatest Show on Earth. In this chapter, Only a Theory?, Dawkins chooses two definitions from the O.E.D. , which he labels Sense 1 and Sense 2. As Dawkins points out both senses are in common use,

Those who put your question on hold, because the answer is just a matter of opinion, should go over to Math Stack and ask if number theory, graph theory, set theory and so on should all be renamed.