Recently, Valve switched up the active duty map pool by removing Cobblestone and putting in Dust 2 into the active map pool. The active map pool is regularly switched around to keep the game afresh and also ensure the maps remain at high efficiency. Cobblestone is a decent map, but the developers obviously felt that it needed a bit of a tweak. However, that being said, there has been no confirmation that the map is going to be reworked in any way. It might just have been removed just to keep the map pool afresh.
D2 one of the most boring maps tactically ever being brought back in recycling old maps instead of having something new. Disappointing IMO, but at least we have a needed change!
— Jonathan Jablonowski (@EliGE) April 21, 2018
However, it does seem that the pro community is not really enthralled by the idea around it. One such example is Elige who has definitely been vocal and disappointed about the recent change.