Re: Why did Zordon let the Rangers leave?
 

They had the storyline right there. You have her lose her powers. If they had to add Kat, do so with Zeo.

Re: Why did Zordon let the Rangers leave?
 

I always imagined Jason, Zack, and Trini getting new powers and going on a secret mission from Zordon.

Re: Why did Zordon let the Rangers leave?
 

This is one of the benefits of the cast restarts. There is no need to replace the cast until the story if finished

Re: Why did Zordon let the Rangers leave?
 

There was obviously a lot of in fighting between the original Rangers. Something happened after White Light to decide the team. Its pretty obvious with how Jason, Trini, and Zack are never around. And why Zordon is in such a rush for them to go to the Peace Conference. I honestly think Zordon was intrigued to have Kat join the team, since she had potential. And had intel on Rita by being her proxy in the past.

Re: Why did Zordon let the Rangers leave?
 

Letting Kimberly leave was one of Zordon's worst mistakes.

Re: Why did Zordon let the Rangers leave?
 

The Peace Conference was important. The Pan Am Global Games not so much though. Aisha left for important reasons. I wouldn't be surprised if Billy had to stay on Aquitar to stay young. Zordon probably figured out the Mellenium Message with Dimitria, by the time they let the first Turbos retire.

Re: Why did Zordon let the Rangers leave?
 

I like that in the newer seasons its usually stressed that being a Ranger is the most important thing when Earth is under attack.