Funny how the people that use thermostats can understand that you can get away without one, although not recommended IMO, and those that don't use them carry on about them being a waste....
Hornet, by having a thermostat it turns off your heat source, if needed, without one, it stays on all the time. So, on a day when your herp room is 40degC your heat light is still blazing away heating up the enclosure, whilst mine has turned off with no heat being generated at all. Oh, it's only 40 watts, it still burns a lot hotter than 40 deg C and it will still raise the temp of the enclosure by at least 4 or 5 degrees. Oh, sorry, of course, you turned off all your heat because you watch the news or check the weather on the net to see what the 'highly accurate' weatherman has forecasted. Well that's great, but for most of us normal people, we often forget things, especially if you have a family and kids.
So for those that are just starting out and aren't familiar with different cage designs, as you can't buy them in a shop, or how to set them up correctly and don't have a flawless memory and never ever forget to turn power off, it is a piece of highly valued equipment that should be part of any beginners set up. Then, once they have established themselves with some experience and want to take the risk without one then fine, go ahead. Or maybe they have massive shed where they can put in overly large enclosures with tons of ventilation so they don't need one as well. JMO