I would be very careful about using an incandescent bulb as a current regulator unless I knew that the power supply voltage rises only slowly when switched on. The reason is that an incandescent bulb has a resistance when cold much lower than its resistance when running at normal power - about 10 to 14 times lower for a standard bulb, more for a halogen one. If you are running the incandescent bulb at much less than its rated voltage, the resistance change will be lower, but there will still be a surge of excess current to some degree when you power the system up.
. However, I've found that this isn't a problem for power LED's. An LED is destroyed by excessive heat (power dissipation). Using incandescent bulbs as current regulators DOES put a momentary overcurrent surge into the LED, but it never lasts long enough to overheat the LED.
Think of the technique of running 7 segment displays directly from uP ports without resistors. Each LED segment is turned on only for a percentage of the total time (i.e. PWM) so that even though the INSTANTANEOUS current is way too high, the AVERAGE current is correct.
Look at "flash" lamps in camera phones. Those use a white LED which is "flashed" with a very high current
for a very short time
. The LED makes a LOT of light (and would burn out almost immediately if run that way constantly), but it works because the duty cycle is so low the LED never even gets warm.