Your transmission could not tell the color of the fluid, even though your eyes can. It's nice to hear that your service improved things, but why was it in need of improvement in the first place? Does your transmission 'cook' its ATF?

If so, then synthetic should improve longevity (so now you won't have to flush it again for, say, 5X as long?).

But they're not supposed to 'cook' their ATF. Dexron is the most over-engineered fluid in most cars. I don't race my car up Pikes Peak these days, but it once spun its front tires virtually all the way from Glen Cove to the Summit (it needed a new upper engine mount bushing not long after that), and the transmission's never missed a beat. IOW, my car has always been seemingly incapable of 'cooking' its ATF (though it never spent day after day in Houston Summer gridlock...).

I have, preventively, when the car was removed from service (for periodic timing belt replacement) anyway, changed the Dexron in my car's Aisin-Warner 4-spd transmission, and never noted any significant (room for) improvement. So I've never been inclined to spend (waste?) my money on synthetic ATF (even though I always use synthetic oil in the engine), including reasons beyond cost: unlike engine oil, tranny fluid is not exposed/subjected to combustion temps/byproducts/contaminants, nor do we want tranny fluid to be as frictionless as possible (it must retain some 'grabbiness').

Remember, if there's something wrong with your transmission (or car['s design]), that's causing it to damage the most over-engineered fluid in your car, then changing the fluid will only treat the symptom, not the cause (any more than blood transfusions can cure, or prevent, leukemia).