Code that never gets executed doesn't slow you down and is pretty cheap in terms of product cost. The trouble is that before you know it the maintenance costs inflate to negate the cost saving from the re-use. The justification I hear is that you improve your 'time to market' and 'time to revenue', which would be fair enough if we had any metrics to confirm the arguement.

The devils triangle of development is;

You want it fast, you want it good and you want it cheap.

Now tell me which two you really want.