They know how well received the ability to make decisions and them carry over into the next game are
While they allowed you to carry your decisions forward, they hardly had an effect on ME2! All it did was change a couple of cutscenes here and there, the overarching story and character development remained unscathed.
[MASS EFFECT 1 + 2 SPOILERS!]
What worrys me, and is worthy of note, is that all of the characters from ME1 that your actions affected greatly barely had a feature in ME2. Wrex, short cutscene if you didn't kill him, then he stood around looking cool but not doing much. If you did kill him, different cutscene but ultimately the same outcome for Grunt.
The two humans from ME1. Again, just a couple of different cutscenes depending on your decisions. Basically replace one with the other depending on who you let die.
Liara. Again, different cutscenes. Never played the DLC so don't know if that has an effect.
The significant returning characters (Garrus, Taali, Joker) couldn't really be affected significantly by your actions. Sure they would/wouldn't like you, but they ultimately were alive and well, hence why they could return. Whether they liked you or not come the end of ME1 again had little effect on their behaviour in ME2.
Now, to my point. ALL of the characters in ME2 were affected significantly by your decisions, they either lived or died. Which brings me to the question; will any of them feature in ME3 AT ALL? If making a characters life/relationship hang in the balance in ME1 meant having them only as a cameo in ME2, what does that mean for all of the characters in ME3? I can't see them recording an entire games worth of dialogue for characters that might be dead before the game even started.
I sincerely hope they don't go the same route as ME2 and just make it so they all die and Cerberus choose to reincarnate a set few, thus allowing them to plan the storyline around them better. It was slightly cheap in ME2 (though i'll forgive it cos it worked), but to have it for the entire cast of characters seems a bit... lame. But then i can't really think of another way of making it so that they KNOW which characters are alive at the beginning of the game.