I use "RuneScape" as an example:
RuneScape, a MMORPG game, went forgeted up, because Jagex (the people who made the game) updated RuneScape with forgeted up stuff, that no one liked. The community went smaller and smaller as the day went. Jagex noticed that and posted "News" about having a 2007 version of RuneScape. What happens if we have a community that prefers the old version more than the new version? Yeah, we would have a lot more users in the 2007 version, instead of the newer and updated version. With other words, we would split the community and ruin the whole game.
Now interpret this into Blockland:
Let's say we have Blockland v19 and the currently Blockland v21? Because a lot of people still miss Interiors & Terrains, a lot of people would probarly play Blockland v19. And the rest plays Blockland v21. We would then have a split community, and this will vary a lot. Because of this, a lot of servers would have circa 7-10 players max. Not really nice. And playing always an outdated version gets boring over time too. The next would be, that those Dedicated Hosting Services, wouldn't have any purpose anymore, because the max player count, wouldn't even go higher than 10.
So, we better stay on the newest version, which currently supports Shadows & Shaders, which loving kills Interiors & Terrains.