There is no reason to say that it is false advertising because it is a vague statement and can be seen as an opinion. However if it is a fact, than it could simply be stating that better ingredients make a better pizza. But either way it is a silly slogan that does not consititute a lawsuit.
Yes, it is my belief that these lawsuits should be curbed because it saves both parties a lot of money and it is mostly about competition which is going to happen regardless. I think that Pizza Hut should let Papa Johns have their slogan because Pizza hut should be focused on their sales not on Papa Johns.
Pizza Hut do have a valid claim that the use of a slogan which implicitly suggests that they are creating an inferior product adversely affected their sales. While it is natural that Papa Johns would want to take business from Pizza Hut, trying to run them down in their slogans is a step too far.
No, business lawsuits to protect branding and slogans should not be curbed. Companies work hard to develop their brand recognition and advertising slogans. It's a big part of their profits. Companies should have a legal path to protection of their assets, including slogans. If their claims are not legitimate, it will be discovered in court and they will pay the expenses.