Re: Why were Wes and Eric able to keep their morphers?
 

They kept the morphers for a reason. It had to be because Time Force new they were supposed to keep them in the current timeline. Wes was needed in the past. It was the real reason why he couldn't go to the future. It wasn't about making his own destiny. If he went to the future all the good was supposed to do would have been prevented. Wes had to stay for the greater good.

Re: Why were Wes and Eric able to keep their morphers?
 

They shouldn't have been able to keep them. It made no sense and had to be a mistake by the writers.

Re: Why were Wes and Eric able to keep their morphers?
 

I do wish they gave a more explicit explanation for this. As great as Time Force was, the finale was a little clunky.

Re: Why were Wes and Eric able to keep their morphers?
 

I agree that this made no sense. There is no way letting them keep the morphers wouldn't change the timeline. Its likely they influenced SPD.