I wouldn't say it's more flexible, as XMonad has all the power of Haskell behind it (+ ability to create sub layouts), and is easier to create more complicated

I wouldn't say it's more flexible, as XMonad has all the power of Haskell behind it (+ ability to create sub layouts), and is easier to create more complicated arrangements than hacking together a bunch of bash scripts - but I think it's a good balance of flexibility:simplicity. XMonad is pretty complicated to configure even pretty basic things.