You could try to recompile Unity, getting the source and changing a .cpp, there's something like Show_Trash(true); and you put false, recompile it all and install it... hoping it work.
I've tried to do that to put a "show desktop" icon, which are set (false), so as some tweaks could easily put a show desktop on launcher, running in the same way, I think it's possible to remove trash icon.
Well, I gave a look at unity source and I saw show_desktop_icon is a boolean, that is why it receive false or true, but that's not the case of trash. Actually is a function on LauncherController.cpp called InsertTrash();, so I think if you want to get rid of it...
Before installing it, you shoud remove InsertTrash(); line 155
I don't think this could worth the time.
The problem with Trash Icon is about another programs, when you do a program for Ubuntu, there's a function to "grab to trash", so if they give us the option to remove it, some apps could crash or something, because they're not made to handle a missing trash. Of course we, as Linux users, could do all this job to remove it, but I don't think Ubuntu is a good distro to tweak, any mistake can brake a lot of dependencies...
BTW, I liked your screenshot, I did the same thing to my Launcher two days ago haha
I read a comment by Mark Shuttleworth on Ask Ubuntu, that the trash icon cannot be removed because it's there by design, like the Ubuntu button to launch the dash. The idea is that the dash button always takes the top place, and the trash the bottom. They do it like that to make it possible to drag luancher icons to the trash to remove them.
I think Ubuntu is a good distro to customize. It's just that you have to find out how to do it. I don't think that's a bad thing, and I don't mind gimping a little or editing some config files to do it - Openbox isn't much different, and I got used to that.
That is another reason, but I think they could use it as a boolean, so this will not be so hard to change...
I see this in other way... This version is extremely unstable for LTS, some changes just crash the system. Two days ago I had to reinstall Ubuntu just because the icons disappeared on launcher, they were invisible and nothing that I could do solved it.
It's really pointless to argue over something like this. It's stable for me, and tons of other people too; it also breaks for many. Same for Arch. There was an occasion when Debian Squeeze crapped itself for me, and it's supposed to be rock stable (which it is, 99% of the time).