So after reading so many people complain about the design choice, I couldn't help myself but wonder if Bay had a reason behind for giving Megatron tusks. At first I thought it might be to match up with a faction of knights since animals were used as symbolism. I did find an elephant but nothing I read about the order seemed to matched up with what Megatron was. But then I stumbled upon an article titled "The Meaning and Symbolism of the Hunting Scenes in Sir Gawain and the Green Knight." My interest was peaked since I was looking for animal symbolism when it came to knights and the articles dealt with one of the knights of the round table which is part of the theme of the upcoming film. So I clicked on the article and read through it completely. Sure enough my eyes widened when I stumbled upon the explanation that seemed to fit Megatron nicely. So in the story, without going into too much detail, the hunter is on his second day of hunting and he is pursuing a boar. The boar was thought to be elusive but prone to face his attacker and strike back. The boar was not easy to kill since he does managed to attack and injure the dogs before finally being slain. The description of the boar does match up with what is shown of Megatron in the movies, elusive for the fact he is capable of disappearing from sight if he wishes, hard to kill not only for how he can go toe-to-toe with Optimus but also for the fact he never quite stays dead, and can cause quite the damage considering even Optimus has had some bit of struggle taking him down and would have lost if not for intervention. There is a chance that this is nothing more than a coincidence, but with how much focus Bay is wanting to put on the theme of King Arthur and the Knights of the Round Table, it's safe to assume this might be where he got the idea from.