That's a very bold claim you're making! String theory is "imaginary mathematics" - whatever in the world that means - with "no practical possibility for application". And precisely how are you in a position to know that? Is that what Smolin told you to think?
Smolin has made claims as extreme as that no one but a string theorist had been hired in years - I'd have to dig up the precise quote, but it was blatantly false. Most of the time he's talking to people that have no other immediate source of information and believe him based on his credentials, so he can get away with it.
That's a far cry from your original claim. Now tell me - who, precisely, would you like to have making such decisions if not physicists? Would you put Smolin in charge, to decide who to hire and what people should work on? Or a committee of non-experts? What will they tell young Ph.D. students that decide on their own that they want to study string theory - no, it's forbidden? You seem to find physicists and their professional opinions - the people whose careers depend on this, who are the experts, spend their days and nights working on the topic, struggling for jobs and publications, who have the most at stake - to be misguided fools in need of some advice. It's really weird.
Again, "imaginary mathematics". FYI string theory has produced several Fields medalists - that's the highest award in math, analogous to the Nobel prize (there isn't one for math), except awarded only once every four years rather than every year. Two string theorists got it, and at least one other mathematician working on string theory. The truth is that ST sparked a revolution in a major field of mathematics - algebraic geometry - and has lead directly to some of the most exciting developments in the entire field in the last two decades.
Moreover it's had broad and far-reaching applications to many areas of physics, from QCD (which was its original purpose) to gravity to nuclear physics to superconductivity and the quantum Hall effect. It's an extremely powerful and versatile theoretical tool - whether it is the correct theory of everything is another question entirely, but without doubt it has had a major impact and made major contributions to theoretical physics and mathematics.
None of that is true for loop quantum gravity. It has produced no mathematical insights, and it has no application to other fields. It is an obscure and small subfield that has gone nowhere.