I also agree that many women do not want to be numero uno. They are, however, very ambitious for their projects to succeed and be well organised, well executed and bring business success - not just financial but also in terms of creating growth and sustainable progress.
What women don't want is huge offices, unless they contain the whole team, subordinates to "boss" and stupid interminable "meetings" to discuss 'points of order' - full of egos and incompetents. This appears to be how men assess their competence, but it isn't what fulfils or stimulates a successful woman.
What women need is to be recognised for what they are - often highly organised, multi-tasking yet extremely focussed. They are very good at delegating what they consider to be simple tasks (sub-projects) only to find that the office "gossip" has described them as weak, neglectful or too busy working flexibly to manage the whole account alone. They don't do well in performance reviews because they don't score points against others - they are busy taking everyone with them as they head for combined success.
Men want to win the game; women want to build a set of people who can interact, who can develop their skills and who can forge ahead for years to come. Maybe if we stop using Public schoolboy Headboy criteria for measuring suitability we will get the boardrooms we deserve?