There was no surprise that Crosby and McFadden were leaving. Word had gone out in TV Guide magazine and in the fan network (which is how we all found out stuff before the Internet) prior to the episode airing.
Actually, there was a
huge shock that McFadden's contract option was not picked up, incuding for the actress. The intention had been that they were planning to write out Troi/Sirtis (or at least try to pump up the Troi character with the bar and office sets, to give variety to her scenes.) Suddenly, it was
McFadden they weren't happy with, so Troi was reprieved. According to Richard Arnold at a convention at the time, IIRC, Gates McFadden had been painted as a whiner, and her character was also "too whiny". Supposedly, she was often suggesting that her character be matched up with Picard, and the writers were resisting. (Another rumour says that Stewart wasn't keen on a romantic pairing for Picard.) There was also a complication with the actress's fine hair holding its style under studio lights; it was causing production delays, which is why she was given an array of red wigs at the beginning of Season Three.
All of these sound petty reasons, but when you realise there was also the harrassment troubles, from someone on the production team, you can see how it was suddenly easier to sweep away all these problems by bringing in Pulaski as a female McCoy. And the setting up of the "Oh, we decided to go in a different direction" story.
It was only by the fan network that we found out why both women were leaving...and we supported their decisions.
There was never a smokescreen about why Crosby was leaving. She was publicly dissatisfied, asked for more to do, and the writers were unable to promise that - and they let her out of her contract. They
could have held her to it for five years, like had already happened with Farrah Fawcett-Majors at "Charlie's Angels" (she failed to report for filming of Season Two, was sued, then ordered by the courts to make several guest appearances), but that kind of publicity can be messy.