The reason Lucas went with a CGI Yoda was so that he could make him into a backflipping twirling ninja who was never supposed to fight to begin with.
Enough said.
I mean, yeah, but it’s also because the TPM puppet looked like straight trash.
I disagree. I think CGI Yoda is the one that looks like straight trash.
While TPM puppet Yoda doesn’t look enough like the real Yoda - I’ll grant you - the same is certainly true with CGI Yoda (both models but especially the ROTS/TPM one). The main difference to me is that I actually think the TPM puppet, despite being inaccurate, at least appears very real to my eyes and actually looks like he belongs in the scenes he’s in. Comparatively, CGI Yoda looks like he was pulled out of a not very impressive video game cutscene and jarringly plopped in the movie. The TPM puppet’s movements and expressions are also more consistent with the Yoda we know and love.