Yes, a remote is useful, I use an Amazon Fire tablet to play music on KEF LSXs via Spotify Connect, but use the remote to control the volume and turn the KEFs off.
Are you sure the WiiM supports Amazon music cast? (Forget the advertising has anyone actually got it working?) I can't cast it to my KEFs, can't even cast it to my Amazon "smart" speaker!
I did a lot of experiments with casting various music services last month, conclusion: Spotify Connect works like a dream, it's wonderful. Amazon Connect and Tidal Connect... total pain.
Does the WiiM support Spotify Connect without any hitches?