'This is the way YOU must roleplay because...' <insert reason here> It is a BIG problem on this server, and your post seems to only further that point. Boxed inside of unbreakable paradigms.
Skip over to the alignment thread next to this one and you will see many people who utterly disagree with your stance. The hair stands up on my neck anytime someone tells me that I must play a certain way because. If you wish to play archetypes with all the nuance of a bull in a china shop that is your right. But it is diametrically opposed to your opening statement just so you know.
These are the goals of saturday morning cartoon mustache twirler evils of the binary sort you describe. But then you go on to state that you prefer this? Mixed messages...Some will want to rule and others will just want to destroy. And yet others again will want to sow chaos more than anything.
Do you truly think a lawful evil thief is going to clearly announce who he is and what his intentions are overtly? Or will he attempt to gain your confidence and trust? Because -you- cannot imagine this character or playing it does not mean it doesn't exist or cannot be masterfully RP'd. Sorry but we will have to agree to disagree on this point.
Too many people here like to dictate how things should be according to their worldview, again, my libertarian sensibilities recoil in horror at it, and it is prevalent sadly.