* Overall it's a very affordable place and people are friendly by default.
* It is a free world Country if you care about freedom
* People take privacy seriously as parts of their daily matters, minimal data share. (unsure about the lucrative advertising business, please enligh)
* Comfortable level of tech, you can say it's low tech, but they got all the details right, and experience is great. (No aggresive behavior analysis, rare ily seen QR code for menu/ordering)
And some realities to offset the love: (Ordered low to high on impact, by personal feelings)
* Unfair compensations, a large majority of companies pays their employees in a Nenko System, basically your salary increments by the x years of service inside the company
* HIGH welfare tax, Nenkin will take away around 10% of your PRETAX income.
* Language, I love this Country and I would like to learn their culture and their language
* Etiquette, the Japanese way of daily routinal interactions are very much formulated, you can take vantage of that when you are fresh off boat and trying to do basic things like shopping and lodging. But say if your goal is to integrate into their society, it's going to be a long painful journey for the talented. I got a few friends spent better half of their lives in Japan who just gave up on becoming Japanese. One of which quitted so well that he occasionally violates social norms.
Bottom line: you will need a strong incentive to stay in Japan and start/move your family here, and your first experiences won't be good. So why would foreigners stay if it's next to impossible to become local. If you are doing well enough in the Country you are already within, then you definitely would miss it and go back.
You could become naturalized there, but you will never be Japanese, and you will never be treated as an equal.