They should have STOPPED at this one

The first was fun and charmy, this one was at least kinda funny, the third was pretty stupid and felt like a rip-off from an old, much better Don Rosa-story, the fourth was practically re-hashed the plot of the second PLUS introduced some terrible, terrible new characters!
Why the hell did the bother to make 3 & 4? This movie really felt like it ended the series, still they continued! WHAT THE *beep*?!