The biggest reason to update a component, aside from radical tech changes, is to differentiate it from the previous one. BAT, for instance, had been producing its VK-300 integrated amps for almost 20 years before "upgrading" it to the 3000 series. It's hard to sell something that may be 20 year old (used), and they probably got complaints from dealers. The 3000 (now obsolete?) looks almost exactly like the 300s. BAT has released a whole new line of electronics (see website).
Balanced Audio Technology
Balanced Audio Technology