Sure but it's not like they do it all the time. They did it with this one specific character, and it ended up making the character a lot better than his initial appearance, as well as helped develop other characters (like Obi-Wan) even better.
Overall, it's a net positive they brought him back and he wasn't so certainly dead via disintegration or burning or something that it made it plausible it could happen, even if it was a remote possibility.
And again, he's an alien with probably different biology from a human and has magic powers. Anything can make sense when that is taken into consideration.