Was the Dressrosa Arc inspired by the Alabasta Arc? I saw this post 2-3 days ago. Here Oda sensei explained why he drew that!
But apart from that I think there may be a deeper reason why he did that.
I think Oda sensei hinted that the story of Dressrosa Arc is inspired by Alabasta Arc.
We know he does that a lot. But if that is true then he is insane. Writing a story inspired by his own story... is on a different level, I think. In the end we see that these two stories has different viewpoint, nature and ambition of Crocodile and Doflamingo are different and a lot of things are also different (although the two arcs share a lot of similarities).
Is it true that Oda wrote a story inspired by his own story?
Well.. it is not stated anywhere by Oda himself (as far as i could search), but there is an ongoing rumor that the arcs in the New world are counterparts of their respective arcs in the beginning of the grand line. 

So, we have Dressrosa as the first big arc since the straw hats entered the New World as a counterpart to Alabasta and Punk Hazard as the New World's counterpart of Drum.

Despite the similarities, there is still no confirmation by any official source that Dressrosa was based on Alabasta.

Annex: List of similarities between Alabasta and Dressrosa