Having 1.7M in AA is pretty pointless -- but I will say that it's not a bad idea to keep a bankroll of points in a number of different programs -- eg: 500K in AA, 500K in Hyatt, 1M in Marriott, 1M in Amex, 1M in Chase, 500k Citi, 500K Cap1.

If you have points spread across many different programs, including ones which have good transfer options, it means that you have far more flexibility in using the miles in the most efficient ways possible, to travel where you want, when you want. If it's all in AA, you are at AA's mercy.