In the Indian context, the forward price of the rupee is not essentially determined by the interest rate differentials, but it is also significantly influenced by: (a) supply and demand of forward US dollars; (b) interest differentials and expectations of future interest rates; and (c) expectations of future US dollar-rupee exchange rate.
To use another example, if one is assessing the distribution of possible outcomes for Brazilian interest rates, should one include observations from the periods of hyperinflation? It would seem a more reasonable assumption that there has been a regime shift and hence that earlier period is no longer relevant.