You don't need temperature control to make beer, you can even make some great beer without it. But if you want to consistently make good/great beer and eliminate wierd esters and keep fusels in check, it is essential.
Temperature control is quite possibly the biggest single thing you can do to improve and control the quality of your beer.
I don't have a fridge. I use a swamp cooler (large bucket filled with water), which maintains the fermentation temperature stable. Unfortunately I don't have the capability of fermenting at a temperature lower than the temperature of the concrete in my basement (the water will take on the temperature of the floor, and not the air), but I can heat it up using a cheap fish tank heater which is good for finishing Belgians.