Partial offers would help everyone out. If a region lord puts up a buy offer of 1000 bushels, it's really frustrating when, as a trader, I can only find 900 bushels in range to broker against it. And I'm sure the region lord needing 1000 would rather have 900 than 0.
I know that I would definitely like someone to sell me 100 more than I would like 0.
Also, when selling, I would like to sell 100 more than I would like to sell 0.
In fact, that's why when I post offers, I just post a lot of 100 bushel orders. If I want 1,000 bushels, I post 10 orders for 100 each. I can't see why anyone would do any different. There doesn't seem to be much point to posting a 1,000 bushel order, unless you already have a trade partner arranged and ready to trade on that amount. There is simply no advantage to doing it.