For smaller maps, open source might be fantastic. Players can learn from that maps how editor stuff works. Since these maps are kept simple, they are easy expandable. Most of these maps rely on only a handful of systems at start. In short: Small, easy, fun = unlocked.

If I would release my map unlocked, maybe most of the people wouldn't know where to change what or may break the whole system (I'm using very less failsafe conditions to debug my complex systems, if it breaks, there is an error I need to find).
For example they wouldn't know which custom value contains which information and may would break a system like the gold for damage% sharing for one player.

Also I plan to encrypt the saved hero&item data, so I wouldn't like to show it to everyone because it would make it easier for them to cheat themselves insane items or just raising their money and stats. So it would be possible for them to create a ring with +9999999hp.

The second one is pretty much a solid reason to lock my map (and many of my comments are a German+English mix).

Anyway, I still share my knowledge and my solutions to problems to everyone who asks me.
And if the maps are old I might even give them my unprotected version.

Some maps should be open sourced but the ones that are very hard to make and ones you don't want people to steal should be locked.
Its a difficult argument to make but i find open source has more negative than positive for a large map. For a game like special forces (easy to make) it just makes the game more accessible to map makers to remake. (there should something to say if you modify it please include my name )

http://www.galaxywiki.net/wiki/Open_Source_and_Closed_Source
Trying to keep this article neutral; if there are any arguments I missed or anything wrong about it, please let me know, or edit it yourself. Be warned, there'll be consequences for repeatedly trying to make the article non-neutral.

I can unlock any map that you can download from battle.net, PM me what you want and I'll send it your way. How about that for open source.

Quote from Veta

I can unlock any map that you can download from battle.net, PM me what you want and I'll send it your way. How about that for open source.

Right, though that is difficult if someone knows how change things so recompiling the map ends up being confusing.

Ya I more so meant to say I support open source and if someone wants to learn from another map I'd be happy to assist them by unlocking it and giving it to them.