I think there ought to be a distinction between semantic flexibility and syntactic flexibility, though. They may be correlated but it's not always clear cut. Lisp is an example of a syntactically inflexible (s-expressions or walk) but semantically rich language (macros).
My own opinion is that syntactic flexibility does have value (e.g. Haskell). I think it's also vastly overrated relative to that value; syntax is incredibly easy to bikeshed. Semantics require you to know something about the languages at issue.
That said, my opinion is that this kind of syntactic flexibility offers dubious value if the trade-off includes not just obviously broken programs but also subtly broken ones with errors which are difficult to spot. Newbie errors are part of the learning curve, but these seem like mistakes even experienced people can make.
My own opinion is that syntactic flexibility does have value (e.g. Haskell). I think it's also vastly overrated relative to that value; syntax is incredibly easy to bikeshed. Semantics require you to know something about the languages at issue.
That said, my opinion is that this kind of syntactic flexibility offers dubious value if the trade-off includes not just obviously broken programs but also subtly broken ones with errors which are difficult to spot. Newbie errors are part of the learning curve, but these seem like mistakes even experienced people can make.