Good observation.
I think it was kind of like they were assigned a story idea…where one of the producers said, "Can you guys come up with a Halloween-themed episode?" And they were like, "Halloween?" "Yeah, Halloween." "Okay, Halloween! We'll do it!"
And the title was a spoof of that discussion in the story conference meeting.

ETA: Looking at the IMDb credits, it looks like all the titles with the "xyz? xyz!" format were written by Brett Baer and Dave Finkel. It must have been their little stamp/gimmick.

That's the best (albeit only lol) theory I've heard. It's just odd that the majority of episodes had normal titles (i.e. they were descriptive phrases or puns, like "Sweet Charity"; "The Goodbye Girl"; "Maya Judging Amy"; "The Write Stuff"), and then there was a handful scattered throughout the seasons with the same format ("Halloween? Halloween!"; "Christmas? Christmas!"; "Liotta? Liotta!"). Perhaps it was the trademark style/format of a particular episode writer.

Huh??? I always assumed it was because it was a show about a Magazine & thats how the Magazines grab our attention.
Im probably wrong but, u know how magazines TRY TO MAKE EVERYTHING AWESOME!!!!!!!!!!!! LOL
I noticed the episode titles too