I'm pretty sure the name "random-face-on-keyboard" names are marked as taken is because they're not allowed. You have to have some semblance of a coherent name. I believe DDO has a sort of filter or something on name input. Just keep trying names you like until one is accepted. Remember, Surnames don't matter, so if it says the name is taken, you don't have to change the Surname, just the First Name.
The reason it won't let you log on to the official forums is because you need to go to myaccount.turbine.com, log in, and create an official forum name before it will let you use them.