Why Minetest? What do we test?
We test your ability to have a strong opinion on names. :D
Now for real: I don't know why it is called “Minetest
The very first name was “Minetest-c55” but it was later changed to “Minetest” (good idea). Fun fact: I played Minetest when it was still called “Minetest-c55”. I'm old … xD
I'm pretty sure the name was taken by celeron55 himself. The “-c55” is obviously from the nickname but that doesn't explain the “Minetest
So you probably should ask celeron55 directly why he chose this name.
But I strongly think (like sorcerykid) changing the name at this stage would be a very bad idea because this name is already pretty well known and a change will only create senseless confusion.
The name is slightly strange but short and pretty memorable. The name is so silly, you won't forget it for a while. :D
Also, I don't think we shouldn't really bother about the name of Minetest because Minetest is just an engine. Subgame names should be more of a concern.