The reason behind the gathered maps being unique is to prevent the 1% buying up every map on the market & cornering content. Yes, I know there's ways to stack via the mailing system but this is time consuming & has a limit.

The newer content from 3.2+ is exactly why they did this as more stuff is relying on maps, like Unidentifiable items & Dragonskin Dungeons. If someone is able to have several hundred maps at once it would severely skew any content relying on maps. Imagine if Dragonskin Dungeons gives out something everyone needs & they access to it is primarily controlled by 3-4 people per server.... Mayhem & complaining would ensue.