Bit of a stream of conciousness I apologise...
really simple one, shouldnt take much effort or resources; tacklers being dragged along a bit in the tackle, eg if a big man runs into the fullback, depending on the size of player in comparison to the strength and size and technique of the tackler, the tackler man only be able to slow the runner, possibly bringing him down after 5/10 metres or so, also depending on where the tackler hits the runner, eg if he tries to take him high, he could be pushed off by a strong runner, but if the runner isnt strong and the tackler is he can wrap him up and possibly turn him over.
Add that to the possibility of gang tackles al la madden, then a weak tackler may be able to slow down the runner and then be aided by a fellow tackler, but if its Parisse being tackled by ben foden and another small man then he may still drag them some way, depending on the cumulative weights/strengths/techniques etc.
basically make it so strong runners dont just either "get tackled or dont get tackled" as the current ver, lets have it so the size and power of the runner is put to pay in the tackle area, and can make the difference near a try line.
PS this can apply to pick and goes, but i think there needs to be an option to crowd the ruck area with defenders, eg when a ruck is formed press down on the analogue to set pillars and how many, so if camped on the try line then can have a load of defenders for pick and goes, forcing the opponent to ship it wide.
also
pre setting individual players would be good, but a bit more technical. eg being able to set how the player/s act in the game when not being controlled by the used, eg how the back row work (be it set to ball winning, defending, ball carrying etc, so the player can play to their strengths) and then if you want to target a weak player in the opposition eg the fly half then you can set the 7 to rush up in defence or the 8 to ball carry in his channel
bit tech but in 04 you could set whether you play forward or back orientated and this isnt that different