Actually, that is how Japanese heroes are usually treated. Rare exceptions exist, but it is usually not the character that continues in a series. Often, they will be killed or re-assigned and a new one will take their place.
Kamen Rider and Ultraman did this for 30+ years. The character of Hatori Hanzo which was popularized in Kill Bill is the UR-Legacy Character. Each Hatori Hanzo had the same name (and same actor) but was a different person who was the son of the previous Hatori Hanzo.
However, over time, few of these hero programs are said to take place in the same universe--or at least on different planets (Super Sentai and Modern Ultramen especially). Which makes such usage sensible.
But, as I said, there are exceptions--and famous ones at that.
Most of these are older characters (Gigantor, Cutey Honey, Astro Boy), but some modern examples exist too (Nanoha Takamachi, Sailor Moon, etc.).
Mecha Pilots often pull a Tony Stark and upgrade their machines (Getter Robo to Getter Robo G; Mazinger Z to Mazinkaizer; Armuro Ray's various Gundam models). However, the previous mecha is usually destroyed before the new one is unleashed in a symbolic killing. It's a big thing.
They do both, but the nature of Japanese hero stories are generally fundementally different from those of the West.