I don't think it was necessarily wrong, just that it could have been done better.
I think Jasper and Bellamy got a lot of hate in season 3 because they didn't put enough effort into depicting the change both of them went through because of what happened in Mount Weather. Bellamy's actions in 3A (siding with Pike and killing Grounders) felt very rushed and they should have explained his state of mind at that point a bit more. Most of the fandom, myself included, had a really hard time relating to Jasper in s3. His story was truly tragic, but instead he came across as kind of annoying, selfish and irresponsible. This is my biggest regret to be honest.
Octavia's rebel attitude at the beginning of the season could have been addressed better as well.
I also think Pike's flashback episode should have been introduced earlier in the season and some backstory on what his people went through with Azgeda, just so we can understand their attitude towards Grounders a bit better.
Just my opinion.
