No argument there, I just think it's also worthwhile from a quality of life + tourism $ perspective.

Ya, but it should be classed in that bucket rather than to alleviate other problems. E.g. there are some nice new recreational bike trails here in Washington and Idaho along old rail road routes. They won’t do much for rush hour traffic, but they are nice to have.

True, though I do think it's worth looking for connections between the two. A rail trail running through an area could form a good route for many different short commutes all along its length. If it's all rural, then sure - there's unlikely to be any overlap. If it connects populated areas, then subsections are likely to be multi-purpose.

That's the case for a lot of the trails in my state - there are big, rural, rail trail loops, but the suburban/urban connections to the routes are excellent commuting corridors.