I have a 2007 Jeep Grand Cherokee and I am not sure if I need to change the transmission fluid or not. I have changed the differential fluid. Is that good enough?
It depends if you want the vehicle to last for the short term or the long term.
Look at all the fluids in a vehicle as maintenance items. Be it the engine oil, transmission fluid, brake fluid, power steering fluid, all these fluids when serviced on a regular basis allow the components they operate in to last longer.
You drop the pan, change the filter, and refill every 25-30k miles. Use ONLY ATF+4 fluid.