Worst case scenario:
HLP gets proprietary; modmakers demand encryption for their mod files so that other people can't steal their work. All mods are lower in quality overall because a key feature that one mod could benefit from, is denied to them because the others have made it proprietary. As a result, everyone is reinventing the wheel the wrong way to do the same thing in scripting that another mod already does perfectly. People "stealing" ideas, people flaming each other because they are using each other's ideas, people flaming each other because they won't give up their ideas/models/whatever. People stop bothering to learn to mod because they are intimidated by large mod groups which keep their secrets to themselves. A general air of fear of other modmakers and infringing on intellectual property within the community; nobody shares, everyone hoards.
As long as there are people willing to share within the HLP community, we're good. When SoL is released and on-rails scripting is given to all, a new "genre" of games for FSO will be opened up. It might be far off, but someday we might be making that "Freespace FPS" as a House of the Dead type game with Shivans in it. A two player (simultaneous or online) rail shooter with full support for lightguns...battle Shivans, Vasudans, NTF...
I think an open source attitude with already-released mods will promote creativity, learning and better quality mods. Granted, there will always be script kiddies following people like Wanderer and Nuke around (I myself am currently a member of their ranks). Sharing techniques inevitably creates clones, knockoffs, and blatant copy and pastes, but there is also a limit to what one can do with mere "cut and paste" scripting, and when the script kiddies reach that limit, they will either give up or become script gurus themselves.