Snape's Worst Memory itself was included, albeit in a very brief and unclear scene which, iirc, was skated over pretty quickly. I don't think it served much purpose at all, just that Harry wasn't the only one with regrettable (although in the film Snape inexplicably never uses the pensieve, so that was his own fault, if anything).
It was a sad inevitability that with it being the longest book in the series, it would have the most content cut in the film adaptation. No Woes of Mrs. Weasley, no Quidditch, no St. Mungo's, no Rita Skeeter, etc. Of course they had to cut it down to something which was marketable and of a suitable length, but for someone who grew up obsessively reading the novel over and over, the end result just doesn't feel quite... there, I suppose.