With two new balls in play, it's important for teams to ensure they don't lose early wickets. Keeping resources for the end overs is key. Batsmen like Alastair Cook, Ian Bell and Jonathan Trott are perfect for these circumstances.
Two new balls upfront also encourages stroke play, which combined with field restrictions, makes the early overs a good time to score heavily. Three obdurate batsmen at the top is not ideal.