The vast majority of those cards are cards that would otherwise be unacceptable here, so that isn't really a valid complaint. There's also the potential for those cards to be released in future if they do become tame enough (Harpie's Hunting Ground and Breaker the Magical Warrior used to be skill-exclusive, for example.)
The 5 Signer Dragons were given only with skills at the beginning of 5DS and certainly they are not op cards. To me it is just a way from KONAMI to earn more money by giving cool cards only with skills and put them in main boxes later to increase the hype to buy them.
It's understandable with Chaos Max though, freely being able to use/summon it without the restrictions of it being locked in a skill would be pretty devastating. Y'know, given its untargetable by card effects,is a 4000atk beater AND deals double piercing damage
honestly it's not as bad as you think lol honestly i wish people would stop playing six samurai though they get 🔥ing annoying to play one after another round of the same boring automatic win deck from people i hate it I want Dark magician to reign supreme for 🔥ing once like Blue eyes gets