Its all about balance. The space is simply not available for the stadium to be 62,000 seated spectators, as the extra space that would be needed for seats will remove the capacity of the concourse. The concourse has been designed to handle 62,000 comfortably, but the space that this has required means that less 'seat' space can be provided. Maybe something will come out of this second stage of consultation, but would be interesting to see peoples thoughts on capacities with a choice of 55,000 seated at day one with capacity to increase to 58,000 with rail seating, or 52,000 at day one with capacity and facilities available to increase to 62,000 with rail seating. Don't quote me on numbers, they're hypothetical, but the point is, constraints of the site make it a very delicate balancing act.