Most code, even more for a sandbox game, is made to be modified.
If it's not well made, it will be hard to modify it, you will add mistakes to mistakes and it will become harder to develop. The last Minecraft update is probably a sign of that (they remade everything if I understood correctly).
Terraria is currently a good example to compare with the situation of Minecraft. I don't know how both is made (except some stuff that my friends told me about Minecraft) but all I know is that most Terraria player made fun of Minecraft in the last big updates because they had SO MUCH content added when Minecraft had nearly nothing more.
If he's trying to write fun games that won't be updated, yeah, it's fine. Except that it's not the goal of Minecraft (at least I hope it's not...).
Terraria is currently a good example to compare with the situation of Minecraft. I don't know how both is made (except some stuff that my friends told me about Minecraft) but all I know is that most Terraria player made fun of Minecraft in the last big updates because they had SO MUCH content added when Minecraft had nearly nothing more.
If he's trying to write fun games that won't be updated, yeah, it's fine. Except that it's not the goal of Minecraft (at least I hope it's not...).