Its still really easy to gem in protective polish in any set, and great for both.
Not having to deal with Elementless jewel is a plus.
In the two sets i made for hammer, not having to use that gem gives two levels of slugger in one set and +1 lvl to attack (4->5) and speed sharpening (2->3) in the other.
Base set is atk4/handi5/WExploit3/prot polish:
I chose to add in focus lvl 3/speed sharpening 3 (slugger 2 vs elementless)
earplugs 5/speed sharp 2 (atk 4->5 + speed sharp 2->3 vs elementless)
The difference in utility is enough to justify Jho hammer's use personally, hell, the difference is so small even a min-maxer like me would choose the more fashionable one. The annoying 5% negative crit aside xD.
Anyways, i don't disagree with you that Jho hammer is the better weapon, just wanted to letcha know that :)