It wasn't only him. It was a DC wide effort to return a bunch of the major 60s heroes and make them take back the mantle from the legacy heroes.
Funny thing about Flash in the JL show is that he's more of an amalgamation of Barry and Wally, the latter of which was also a forensic scientist in their civilian life.
It wasn't Johns as much in this instance as it was Didio and Morrison. They wanted to bring back Barry during Final Crisis and Johns was tapped to do Flash Rebirth.
Because the obvious answer is Guy.
"Pulled a Freeze"I don't think it's a coincidence that when they adapt Flash, the characterization is more Wally than classic Barry. Though I like the forensic scientist bent. When we're comparing similar situations like when Hal came back, he at least had a very different personality than Kyle, John and Guy. (though John is one of those characters who I feel pulled a Freeze and really came into their own in adaption)
Barry never really had a strong personality to begin with and I felt meant much more when he was gone. Though I've gotten a lot more settled with it all these days.
The anchoring moments are truly echoing scenes I'm remembering from my classic Mark Waid Flash comics.