Why are lightbulbs considered resistive load?
The reactance at 50 or 60 Hz is simply negligible. According to this calculator a coil of 100 turns 1 mm diameter, 25 mm long is 0.04 &micro;H. At 50 Hz that's 12 &micro;&Omega;. A 60 W bulb at 230 V has a resistance of 880 &Omega;, then the 12 &micro;&Omega; is only 0.014 ppm of that, and the cos(&phi;) = 0.999999999999999902. Shall we say "1"? 

The filament isn't coiled to add reactance, but to increase the resistance, by making the filament longer. Higher power bulbs don't need the higher resistance, and therefore often don't have a coiled filament. The alternative for increasing resistance would be to decrease the filament's diameter, but then it would become too fragile.