Villains is going behind the island so there’s no space. Currently the land consists of talking bears, Tom Sawyer (the Mississippi river), a Louisiana Bayou, and an old mining town. None of that outside of BTM fits the West theme for the land for a while now, it was more a theme that fit and worked in Disneyland that got copied over to Magic Kingdom. And truthfully, the theme of the Wild West of the 19th century still has a lot of racial undertones seen from the train that I’m glad will be removed and hopefully fully updated with this new land. Tom Sawyer’s Island takes up a massive amount of space in a packed park for a child play area. It’s getting replaced with a new child themed land with 2-3 attractions they can ride, themed dining, and shopping while opening up new paths to help ease congestion in Frontierland.
Sure losing the river/ TSI sucks, but if you never remove anything, there’s no space to ever add. Think of how many great attractions exist today only because old ones were closed and torn down.