It's a topic we have debated a few times.
Do you recognise that you only have 45 overs to bat and you need your best batsman facing most of the balls, particularly to deal with the better bowlers
or
Do you take the pragmatic approach and say we need to shield our best batsman for a few overs to come in when they have less chance of getting a good ball
In some ways the wicket determines the approach. Play on good decks and the new ball isn't much of an issue. Play on a bowler friendly deck and the pragmatic approach can win games.
I personally liked to attack the new ball, sending in an aggressive batsman to put the opening bowlers on the back foot. You can draw the sting more quickly out of an attack if somebody smacks 30 in 5 overs up front. However, you also die by the sword if the batsmen get out being to aggressive. Having somebody "steady" in the top order is important either opening or further down, just a case of where.