I dont, only because of the fact that my equipment running keeps it a 79 degrees in winter and in summer I hate heat and keep ac set at 71 which keeps tank at 80 or 81. I do have a heater in sump set to kick on if tank dips below 74 for some reason. It hasnt kicked on since the tanks inception.
If you need to run a heater, do so with an external controller and temp probe. Doing it this way, you will have redundancy in that if the internal thermostat fails, the external controller will shut it down before it boils your tank.
My heater rarely kicks on, if ever. In fact I had more issues with it than anything, especially last year. If you keep your ambient room temperatures around 70 degrees year round I am sure you can go without a heater.
Thats the key.....It really all depends on the temp in the room. Depending on where you live & what temp you keep the room at will determend If you need a heater or not. In some areas you may not need a heater....However In some areas you may need a chiller.