Yeah, the raise preflop is 100% necessary and profitable. It actually might be better just to shove for 20bb there since KJo is somewhere in the middle of your range and is a little too strong to raise-fold but too weak to raise-call. Don’t assume your raise was bad just because you didn’t win the hand.

I’d probably prefer to check that flop more often than betting – there are a lot of draws out there with which villain can check-jam, and if you’re betting the flop then it’s hard to find a way to bet-fold there. Betting isn’t bad though, and against passive players it could be better than checking.

On the turn it’s really a question of what hands villain would actually play this way that you’re behind – a strong Queen would surely either shove preflop or check-raise the flop (or maybe lead out), and pocket fours would likely do the same. QJ would likely check-raise flop plus you block the J, J4 and J3 are unlikely but feasible depending on how wide villain defends the BB, and Q4/Q3 the same if villain doesn’t check-raise those on the flop. 43 is very unlikely.

It’s definitely possible that villain can have a Qx of diamonds hand here, but there are only a few combinations of those out there. There are also some combos of hands that had a straight draw on the flop and turned a flush draw that could play this way, but those are slightly less common, and there are some Jx of diamonds that could do this also.

I think the whole hand boils down to how you expect villain to play their draws on the flop – if they’re check-shoving all their decent draws, we can probably bet and call it off reasonably comfortably, but that also means that their range on this turn card is a bit stronger since it includes fewer draws. If villain is playing a lot of their flop draws more passively, they can have a higher % of combo draws on this turn card that might shove after picking up a flush draw, and that makes calling this bet more acceptable.