Here is John’s reason from a recent interview why he rerecorded his music. In the linked interview he gives his thoughts on all the CCR problems and controversies. I haven’t heard Legacy yet so I can’t comment on that.
Interviewer: After waiting over 50 years to regain the rights to the Creedence catalogue, why did you decide to re-record the songs rather than package up a new greatest hits?
John: I think some of it was realising I’m never gonna be offered a chance to own the masters – none of us in the band will ever get that opportunity; they’ll be owned by a company, and another company, and it all gets very corporate. So, approaching 80 years old, it just seemed like, ‘Gee, what would I like to do? Well, I’d like to have some recordings that I actually own so that I get to control their destiny,’ you might say. There was a lot of impetus from my dear wife, who kinda envisioned the idea of me having an album made up of re-records. It gave me a project that was actually pretty difficult. It wasn’t like falling off a log.