Spielberg didn't really like the Macguffin, and only made the film because he felt he owed it to Lucas. It wasn't until they added the family dynamic that his interest perked up. Despite this, he still had a great time making the film, due to the on set camaraderie.
Of course, the only problem for KOTCS haters is that the film I just described is LC.
Major West said:
I think the people that dislike KOTCS are clinging onto every bare thread they can as ammunition against it.
The trouble for most fans is that they are perpetually stuck in the mindset Spielberg had in 1981. They want every film to be approached with the same seriousness as ROTLA. But the reality is that the Indy sequels have
always meant something different to Spielberg. After ROTLA, he felt he had already said everything there was to say. So the films became more of a guilty pleasure for him than anything else- as well as a chance to reunite with old friends.
He wasn't that excited about directing TOD, and nearly relegated himself to producer when the script wasn't ready in time. Lucas was afraid of losing him as director, and had to urge the writers to pick up the pace.
And Spielberg has repeatedly said he only made LC because of his promise to Lucas, and to make up for what he perceived as a disappointing film (TOD). He didn't think the Holy Grail was an interesting Macguffin, and it took Connery as Indy's dad to even get him excited about the project. Even then, he purposely tried to frame the movie as the final entry, because he wanted to move on from the series.
So it's definitely clutching at straws to try and argue that Spielberg didn't want to make KOTCS, since he didn't really want to make
any of the Indy sequels! If fans had been online back in 1984 or 1989, I'm sure they would've tried to use his candid remarks against those sequels as well.
Regardless, there's no denying he clearly enjoyed making KOTCS. He says he formed a strong friendship with Harrison Ford that had never existed before, and is even willing to direct further installments of the series. It's kind've hard to spin a negative conspiracy theory out of that, no matter how hard you try. Spielberg already cites LC as his favorite Indy film, and it wouldn't surprise me if he ranks KOTCS much higher than TOD (or even ROTLA for that matter).