re: Has any show gotten so much better after a character left than better call saul

I don't think it's that complicated. Chuck was a well respected lawyer (self-made, no legacy) and his little brother was a frickup. Chuck respected the law, he revered it like a religion. It was everything to him. After bailing Jimmy out over and over, he gave him an ultimatum that you come back to New Mexico with me and I'll set you up with a mail room job but this is the last time I'm bailing you out from your shenanigans. If you ever frick up again, you are on your own, cut off, no help, I don't care if it's a parking violation. This is your final chance.

Jimmy followed all the rules, while working in the mail room, went and got an online law degree and passed the bar, without telling anyone, all the while not fricking around hustling people.

It was a shock to Charles when he found out. Everyone at the firm knew Jimmy as the likable "Charlie Hustle" but Chuck knew what a firecracker he really was.

I don't think it was resentment at all. Chuck didn't want that liability employed at a firm with his own name on the building, a BAR accredidation to Jimmy was like giving a chimp an AK47, in Charles' words.

He didn't want Jimmy anywhere near his own legacy that he built over decades, unless he was the mail clerk. Charles is very supportive of Jimmy working outside of the firm, doing public defender work, a very honorable and noble pursuit of the law, until Jimmy starts ripping off Chuck's "NIL" so to speak on billboards.

It's that simple.