In the period between 2010- current, India has the highest W/L ratio of 1.92 against Test playing excluding Bangladesh and Zimbabwe, The next best is SA with 1.35. If we include BD and Zim. India's ratio gets reduced to 1.79 (Thanks to the 2 losses in two games against zim in 2010). Where as the next best is again SA with 1.55 followed by Australia(1.28), England(1.23), Pakistan(1.09).
The most important reason why India is at the top is they have w/l ratio of 2.28 since 1st may, 2012 (ICC rankings give more weight to recent victories).
Away from Home, India has a W/L ratio of 1.26 since may 2010. Since May 2012, India has won 12 matches out of the 15 matches they played on foreign soil. This gives them a W/L ratio of 4.00, The next best is PAK with 0.76.
As far as Pakistan not playing at home is concerned, Its your own doing. You can't expect players to come to your country when they are directly attacked. Had Pakistan provided enough security for the SL players then, You would not have seen such a day.
Even if Pakistan played at home, I don't think you could have challenged India's position at the top of the table.