Not only that, but Java's reflection features opened the door for a huge, vibrant modding community that is arguably one of the largest among any PC game.

Very early in Minecraft's development, people were already decompiling/modifying/injecting their own mods, and a lot of frameworks (Bukkit, Spigot, etc.) emerged to provide a common API for modding.

The large modding community arguably had a very positive impact on Minecraft's early success -- Although I don't have any quantitative metrics to reinforce that point, I fondly remember early Minecraft as having a relatively technical community that tinkered with the game as a sandbox for countless custom experiences.