Penang was a popular destination for retiring Japanese even in the late 80s (esp those who cashed out/retired before the bubble popped). I think at that time it was more 'developed' and international than Thailand (even Singapore then, for the richer), which (along with some other places) has since caught up. And both (and other places) have gotten more expensive than they once were.
#1) Unspoken in videos/articles about retiring abroad (and this goes for all versions of this) is that the retiring person/couple is willing and able to leave family behind. For example, my wife and her sister have taken care of their mother (now in her mid 90s and in one of those 介護施設 places) for years now. My wife still visits her 2-3 times a week. A time or two, her mother has been transferred to a hospital for some treatment, then back. My wife's sister may have been able to handle everything while my wife and I 'retired' to Penang (we'll just come back when she dies?), but that's less than ideal on all sides.
#2) Unspoken is that the retiree couple has kids, who may have their own families. I suppose the retiree couple could choose to visit their kids and grandkids once or twice a year, and that would be enough. But others are more engaged with their kids than that.
#3) Unspoken is that the retiree couple (in addition to family) will have no social network to speak of, or that they're willing to leave those people behind. Or hobbies as a component of that network, which could be more location-independent (photography), or more closely tied to Japan (eg, taiko/shamisen).
#4) While "healthcare is great" in SE Asia, unspoken is what happens and what life will be like there when a person needs longer term care--some level of assisted living, or where licensed care-givers/nurses may be at the facility 24/7. Even for a gaijin like myself here in Japan, this angle is of some concern (and this has been discussed on the RetireJapan forums)--how well would I 'fit in' and be accepted at the kind of place my mother-in-law is at now? So, lots of videos/articles about how wonderful eternal life can be in Malaysia/Thailand/Panama/Costa Rica/etc, and while I might die in my sleep after playing golf the day before, I've yet to see a video/article on what is called 'long term care' in these same countries. Even whether it's available or not (oh, you'll go 'home' for that?).
There's a song lyric that goes, "The sun always shines on TV." I think that's something to be considered when watching these videos.