why is the butchers bridge only temporary?

this seems like a gigantic waste of resources to have the map on shelf, just to whip it out for a single week once a year.

as far as i can see, the layout is exactly the same of the howling abyss. its basically just a really fancy map skin. so why not do it like it used to work with these maps and have them randomly chose a skin for each game, but available throughout the entire year?

with the bilgewater theme, its not really a seasonal thing like with the halloween summoners rift, or the winter summoners rift version. is there really any argument against having the map throughout the year?

at least this way, all the work you put into the thing actually goes to good use. map skins are a thing ive personally been missing.