In a RHD car designed for right hand drive, ie indicator/high beam on the right, I can use the indicator *and* change gears at the same time, as the right hand can use the indicator whilst still on the steering wheel and the left hand can be used to change gears.
In a LHD car but with the steering on the right(like most Euro cars and US cars) the indicator is on the left and so is the gear change, so you can't do both at the same time. It's not a big deal, it's just that it would be quicker and easier to have the paadle shifts on the steering wheel.
Many a time I have come up to a corner, or need to do a lane change at a moments notice, and I need to change down at the same time as I want to use the indicator, so it is an either/or scenario rather than be able to keep both hands on the wheel and do both at near the same time. Paddle shifts on the wheel would alleviate most of this problem as my hands never need to leave the steering wheel and thus both indicating/high beam switching and gear changing can be accomplished at the same time.
As for high beamimg, ever come up to a corner where you want to change down only to find that a car is coming the other way and you also need to dip your lights? Hard to do both at once when the high beam switch(on the indicator stalk) is on the same side as the gear lever and therefore your hand is required to do both at the same time.