@SL Chulbul was never his original name na. He changes it to Chulbul for his lover & enrolls to the police job with that name.
They believed a prequel would have this as a surprise element. In short they weren't truthful enough to the character. The idea of how Dhaakad became Chulbul sounds good, Bhai taking credit for it is also justified. The screenplay should've done better justice to it.
This is why despite having the material to work, they didn't deliver on it.
Whatever they showed in the trailer was just the quirky side of Chulbul which ofcourse less quirkier than the original. Apart from introducing Rajjo's character, rest all were his character traits only. Just that in the film it wasn't well written with depth & neither the execution was crisp. Otherwise the nostalgic feeling is intact throughout.
All the goons who got beaten up by Chulbul in 1&2 are working as labourers in his house now is a cracking idea. But then it gets ruined due to cheap humour. You don't want to see the goon hiding in the kitchen & watch Chulbul-Rajjo romancing & even commenting on it. Chulbul was patriarchal & he didn't like anybody trying to impress her in part 1. He was that possessive. Here in the name of being progressive, the whole team came out as fake & ruined the characters.
This very idea of prequel + sequel could've been presented far better. Could've retained how entry of Saiee in his life brings some positivity & how the bitter relationship with his stepfather could've ruined his love story. Balli Singh using this further. Rest all being same, this could've created more grudge between son & step father. But that would ruin the beautiful father-son bonding Dabangg 2 created. You see couldn't have created too much grudge. The stepfather was lenient to his own son. It's a tricky thing with prequels. No matter how much we argue, the product isn't changing. It was a winning script, bogged down by predictable dated screenplay & bad insertions of cheap humor & forced songs.
Dabangg was not the film with - intro+fight followed by song, heroine+comedy+song, emotional drama+conflict followed by song with interval bang. Then drama+light comedy+song, more conflict+twist+song, final twist+outburst leading to climax.
This was not the template of Dabangg 1, they made to do this the template of Dabangg 2 which didn't work for the movie but audience forgave. Following the same template for an idea that deserved more skill, gave the film up & hurt the franchise.