well, like i said, i have no problem negotiating a deal involving my uu before i set it up(in fact, i always do that).
but, for example, on the black market i said once, i will buy any quantity of uu for attack turns, at some ratio. and i wouldve accepted all deals in the morning(say i posted that before i went to bed) at that ratio, and if i was any turns short, id wait until i get them, and before deal expires of course.
but what if player wants to offer me a deal at lower rate then i said?
i would have to "hunt" him down on msn or something(if he even has one), to find time when hes on to reject his uu, so they dont get stolen,because i woulnt want his account destroyed, just because he offered me unreasonable trade, and i dont think thatd be fair to him.
basically, what im saying is, i am responsible for my own actions and deals via broker, but i dont want to be responsible for other peoples' , and i would be even if i dont do anything, let offer expire that is, loss of their uu would be on my soul, and i didnt do a thing about it - and anyone can place the broker deal even without black market thread or anything.
i can also think of numerous other ways to avoid this problem(for example "agreeing" on the offer through some kind of system similar to broker, and each player would have to click again to have goods taken from his account, or "scripting" - say, i offer my uu, that would be untrained from say miners, when other party accepts the offer).
but i realise none of these systems would work well in practice, because they are just too complicated - and i dont think we need to complicate this game, fun and even complexity comes from simplicity in its core.
and, again, when i posted this,i thought this system should be used ONLY for uu, if naq system remains as it is(its already more exploitable then this). but, this system might be nice for naq also, it would force people to use naq at once, and not to have it in the bank and use it in chunks any size - this would of course be only in cases in which naq ends in the bank now - if youre the offer maker. if youre reciever, it would be in the open.
(i just thought of this, inspired by your repeating that this system is exploitable, especially if used for both resources

)
P.S. just to make clear, im talking about hypotetical situation here, i wasnt in it before, and i hopefully wont,