I doubt Luffy really "needed" G5. Moreover it's just Oda's go to move now, as it's just the better version of his non awakened self, so I wouldn'r read too much into it.
And I like that Monster form. I was right for years, finally it gets confirmed.
It gives relatively weak fruits the potential of becoming op, especially cause they go in hand with haki.
Lucci just had bad luck here tho. He encounters a guy with sky splitting CoC, FS, adv CoA and arguably the strongest Zoan.
Your Zoan awakening can make you a monster, but it can't surpass that. I'm interested to see if he stays fast in that form.
Man I like that concept a lot. That Dachshund DF can make you more powerful than a Spinosaurus or a Mammoth DF. It's crazy, but very fair in a sense.