I do not like the pirates that just say "X Million or you die!", eihter but normally the pirates that do not do this way get in trouble. Many trade that find a polite pirate that tells from his poor childeren or something like that are very happy, because there starts a talk that needs time. While this they look up for police/military/navy/bonty hunter/... player next to them and call for help. Often the hgouse forces are there before the trade really needs to pay. I understand that pirates try to quick, because I normally have this problem. I play RP-pirate and then the forces come to take me and I get around one trader's money. That may be funny but it is also bad for my pocket.
Another reason for this qucik "X Million or you die!" is often that pirates fear of trader passing them because they still argue with ohter traders.
At least I see not real solution for that. Traders shoul be able to call for help and so pirates musst be quick.