Do I really need a thermostat?

Don’t assume that removing the thermostat is going to help. More often than not it will make the problem worse. Thermostats, aside from limiting water flow to the radiator when the engine is cold, control how fast water goes through the radiator. This may not be a big deal with the car sitting still and the engine idling, but once you get going, the faster you go, the faster the water goes through the radiator. Unless you slow the water down, it does not lose enough heat as it goes through the radiator, and the car will overheat. If your car overheats, find out why and fix it. Sooner or later it will cost you money.