What happened to Indiana Jones?

So I guess this blog is just a random thought going through my head. Since I've had some free time here, I've been watching a bunch of movies. My wife was wonderful enough to alphabetize my movies and I just got through watching the first 3 Indiana Jones movies. Man, I forgot how great those movies are. I think one of the things I love most about the movies is the how mystical, yet enchanting they are. Even if it was the Ark sucking the life out of Nazi's, some pagan dude ripping the hearts out of people or Dr. Jones walking across a bridge of faith and fighting the 700 year old knight. These three movies had a plot line that pulled you in and made them a part of Hollywood history (and if you try right now, you can hear the Indiana Jones theme music playing your head). But I have to ask, what happened to the 4th installment to this series. Was the general public begging for fourth movie so bad that they had to stretch so bad as to bring aliens into it? I mean, when Harrison Ford and Steven Spielberg read the story they were like, "whoa, we have a real winner here". Don't get me wrong-it was an entertaining flick but it seemed like it lacked something. In fairness, I only saw the movie once and that was right when it came out in the theaters so I'm willing to say I need to see it again and give it another go round. But still...aliens. OIY!!!