There are some long running TV programs and I suppose each program has reasons why they survive. Generally, they are high quality and of family viewing. Sazae san has a 35 year history.(its original comic was released 1943!). Here is a good introduction. We can see Sazae san's calm happy life. No accidents and no violence and we see their life go through each season's transition with a smile. The interesting point is the setting, the background of the story is always of the present. It has not changed in 35 years. Mom wears Kimono and live in Japanese style room and nobody use's a PC at home and I suppose nobody use a cell too. But it is okay. this is Sazae san style. Nobody complains and actually for Japanese this unchanging life would be comfortable to live and so Sazae san can still create good ratings, every week.
On the other hand, some people have Sazae san syndrome. Sazae san has been shown at 6:30 PM every Sunday night for such a long time. For Japanese, Sazae san is a symbol of the end of weekend. So some people get blue when they listen to the ending theme of Sazae san.