Everybody is scared of being sued.
ANYTHING you say as part of a reference is subject to the
most nitpicking imaginable:
"He was a valuable employee, who made many contributions
and was a great resource. Everyone loved working with
him, and he continuously pushed for better quality and
production output"
So, what you are saying is he cost too much, stepped
on toes, and spread himself too thin. He also smoozed
when he should have been working, and was a royal pain
in the ass to everyone he wasn't shmoozing with. No wonder
you fired him.