Because you may not have the code of a BSD license derived project?

It seems like you missed the whole point of GPL. The *software* should be free. If you can't use a GPL licensed piece of code in your non GPL project, it's because the owner of that piece of code knowingly decided exactly that when he/she chose GPL. You seem to think RMS forced anyone to use GPL for their software, so you can't use it to get back at you. He just made some software under GPL and as the rightful owner of his code according to existing laws, he decided to put such restrictions on it. If you don't like it then tough, maybe you have a problem with this whole copyright law? He is using copyleft to point out the pathetic consequences of having such laws in place. Instead you go and say how come I'm not free to use his code the way I want? So I'm not free and RMS is a hypocrite! Because he keeps talking about freedom and yet I'm not free to do what I want with his code! In RMS's utopia every program is under GPL so everybody can use any other software in his/her project. Anybody who chooses GPL for their software, takes another step in that direction, and as a reward for him/her, everybody else who have or will choose GPL for their software will reward him/her with giving permission to use their code. And if someone does not agree with this idea? No problem! You're just not invited in this private club. I don't get why people get bitter over this?

Why stop there? Following in the general direction of TFA I present to you my kitten pics archive:
{
"fluffy.png": "59 6f 75 20 72 65 61 6c 6c 79 20 6e 65 65 64 20 74 6f 20 67 65 74 20 61 20 6c 69 66 65",
"haters.png": "49 20 6d 65 61 6e 20 53 45 52 49 4f 55 53 4c 59 21 0a"
}