Besides all of the above....
Ive written programs that started out on ancient non-PC machines using languages too embarrassing to name which have since then been modified and converted to other languages. The result tends to be something that I would have to do EXTENSIVE rewriting before I would EVER let anyone else see it.
And there are people here who will never let me forget that.
We might (slim might due to the many other reasons mentioned already) get everyone in Illwinter AND Shrapnel to give permission for others to pursue an open source project completely duplicating Dom3 with full permission to use the name. I have seen that done in the past where the original developers did not want anyone else seeing their spaghetti code or their secret coding tricks. But as I said that would be slim.