With interest rates being so low, you may be getting or able to get a higher deposit interest rate than you are paying on your mortgage, especially if you have a good tracker rate. In this case, you are financially better off to keep your money on deposit.
This also assumes that you are comfortable with the security of your deposit.
This situation is not likely to last. When interest rates rise, deposit rates will not go up as much as mortgage rates and we will be back to the traditional situation that you save more money by paying off your mortgage.
As niceoneted says, there is a nice feeling of not having a mortgage.