It is generally accepted that there is a significant economic imbalance between the South and the North of the UK. Economic pull factors such as salaries and available skills often dictate where talent will travel as well as where businesses will estbalish themselves.
Considering the fact that the Tier 2 (General) category is ultimately tailored to allow businesses to fill skill gaps in the market, one must ask whether the Immigration Rules are part of the imbalance that exists in the UK. Migrants will now be required to demonstrate that they will receive an annual salary of at least £35,000 in order to achieve settlement so, naturally, overseas talent will gravitate to economic centres where higher salaries are easier to achieve (i.e. London).
Perhaps the criticism made by MP's in response to this salary threshold (i.e. that it is "simplistic" and "crude") is not entirely without merit.