shouldnt we have a possibility of conquering the player's cards when we kill him?

That is not a bad idea but it isn`t totaly fair. What if you take over all the lands of a enemy after a big and long war with him. You can however not see his last territory. Someone else (who hasn`t fought in your "war" ) can see this territory and takes it over after you have taken the rest. Than he will get all the cards while you have done everything...

I agree, what would be fun in roleplaying games would be to have a surrender where you surrender to a certain player, giving him/her your remaining territories, cards and armies.
but that would have to be a roleplaying only option, and would only work in ffas. it definitely wouldn't apply to normal games because people would want to take revenge on whoever defeated them instead of helping

i like the idea of the surrender to someone option. especially for FFAs that makes sense as a power move.

for teams it could also be useful, if you want to deliver the rest of your game to your teammate, to get bigger bonuses or in case you have to go on holidays.

thats called "gift cards" ps :)

If you could surrender your cards to a certain player in an FFA, you may surrender your cards to someone besides the person who destroyed you, to get revenge. What I'm saying is you could essentially gift your cards to a player you know would beat the guy who defeated you.