While Lakshmi, Susano'o, and Byakko ain't the toughest EX primals, underestimating them is the last thing you want to do in PUGs, especially in groups that have low dps and/or have the tendency to flub mechanics often.

Shinryu may not be as hard as Thordan EX was at launch, but most people still struggle with that fight too. Most don't even get to the add phase.