Whoa, getting a bit heated there. It's just a light misunderstanding, no need to get all pissy, over an unreg too. This line's been fed to me a good dozen times so I'll use it now: English is NOT the first language for some (many?) of us here, and even among those who it is, discrepancies in vocabulary and statement often lead to small issues like this.
Unreg is just under the impression that you're denouncing these "thieves" and calling them useless in general versus useless to you in your current situation because when people were trying to say they were useful in some way, you pretty much went "meh..." 3 times and didn't respond to the "useful during other collection events, not just MC (DC? I don't play the DMM version) daily. Anyone who has a notable degree of pride and investment in such a character could easily take offense to anyone being that dismissive.
There's also the note that refusing to invest in a class early on and putting it off for later usually results in that class being totally abandoned. Doesn't happen all the time but it does give that impression, I'm just saying.
Personally I don't care. I only have Nutaku Aigis so this class is something I'll get to when it comes but for now, I'll treat it as nonexistent since it literally is for me.
As for me, worst units...
Speaking in terms of Nutaku Aigis, of the classes I'm familiar with I'd say I have the most trouble understanding the value of ninjas (more specifically the iron/copper ninjas). I see them being used in event demonstrations from time to time but frequently their damage rating is so embarrassingly low that short of the standard goblin, just about everything can kill it. I tend to go pretty far off the books in UP spending so for them, if there isn't a specific reason the ninja is being used (sniping a mob on another road), I tend to throw in my Valkyrie instead, and have a princess replace where I'd use the Valkyrie if need be.
I get the value of ninjas in general...when it comes to platinum(gold) and up, but the times I see the youtube vids use copper ones still irks me. It's not like they help with the damage OR can effectively stall any mobs so why deploy them if they don't have a practical use like min-costed bronze soldiers?
(Picking a fight with an unreg is both unproductive and immature. Easier to just ignore them since if they really want to drive the point, they'll get accounts themselves. Staying unregistered (even when they have accounts) more or less leads to the idea that they aren't taking it seriously)