VIP 2 did justice as a sequel; it had the same house, the same characters and the same leads, but the story was bad, there was nothing new, they lost it. On the other hand, we have hit sequels with the same franchise but there is absolutely no logic. Take Lawrence’s Muni or Kanchana Series for example.
Lawrence married Vedhika in Muni-1 but in Muni 2 – Kanchana he courts Lakshmi Rai, but his mother is still Kovai Sarala and his father from the first movie, Vinu Chakravarthy is supposedly dead and his photo hangs in the wall and Lawrence gets a new brother out of nowhere. The third movie has a different heroine, so does the fourth. However, his mother is still Kovai Sarala.
We do realize he is retaining only the things that worked. But using new heroines in each movie because they are just fancy dolls to attract the audience and apparently can’t be used more than once seems bad. The Singam series is another example, though the movie retained the same leads and made sense to everything they added, it doesn’t quite fit why there are second heroines who always fall in love with Suriya ( who was married to Anushka in the first movie, yet gets engaged and marries again) and be alive or part of the movie till that one duet song.