I think the basis for migration has usually been some variation of a "better life for me/the family", and sounds like we're kind of in the same boat now (sorry about the pun). My wife and I came from Germany and India 40 years ago, and made a really good life for ourselves in the US - still probably the best "meritocracy" in the world, for the most part. But now, to use Mazlow's hierarchy (see Dad, I did actually learn something in college), I feel like we need to pursue intellectual freedom and growth while minimizing stress, which is leading us to look at Portugal. Taking the rose-colo(u)red glasses/specs off for a minute, this is probably not a "better in every way" situation for everyone, but it sure looks like it (or close) for us. Like you, our kids are established, so we no longer need to worry about anyone else, except my mother-in-law in Germany, so its basically full-steam ahead! (sorry again)
Your ancestors would understand why!