Lower temperatures are better in that they are lower. It may improve processor longetivity, but a 10C difference isn't the make or break. Neither is worth another cooler or AIO. Outside of that, I am not sure what you are getting at, lol.... does it warrant such a spend on new cooling to have it 10C less? Nobody can tell you, oh yes, if you drop temps 20C, that CPU will now last xx years as opposed to xx when running at 80C. This CPU is so far from throttling and protecting itself, I'd worry more about the constant load and voltage than I would temperatures.ED, that's the question I'm asking you? If cooler is always better, better to what end?
I don't disagree with your overall conclusion that for the OP to spend more money on better cooling may not be a wise use of money I'm just wanting to know why you say in one place better cooling is always better but in other places you say it won't make the CPU last longer or perform better. So besides those two measures of what is better, in what ways can better cooling be better?