WHBM is wide of the mark on the regulator's approach to setting Heathrow's airport charges. The CAA is very relaxed on 'pre-funding', ie making today's users pay for tomorrow's capacity. Heathrow's charges were increased before T5 opened, a deliberate policy decision by CAA to avoid sharp changes in user charges.
I agree, however, that the CAA needs to be tough on 'gold plating', certainly much tougher than they were with T5. BA and easyJet have already made this point.
As for land costs etc, such issues are likely to be addressed in the upcoming policy document from CAA setting out how they would approach the future regulation of Heathrow if a new runway is approved. The CAA will focus on its statutory duties, which include a requirement to take into account the ability of the airport operator to finance the new investment.