Is using indexed view with no expand on standard edition a must?
Why the behavior is not the same in all editions as we have free
  workaround?


You have no workaround in case when the poorly performing query does not use any wiev at all.

You can have a situation when some application does some aggregations and with the large volumes of data it became slowly. In case of Enterprise Edition you can create an indexed view that query optimizer could be able to use for this query even if a query does not access any view at all. And you cannot use this approach in other editions as you have no control on the application source code.

This case is described in Paul White's article that you mentioned about:


  Enterprise Edition and View Matching
  
  On an Enterprise Edition instance, the query optimizer may be able
  to use an indexed view even if the query does not mention the view
  explicitly. If the optimizer is able to match part of the query tree
  to an indexed view, it can choose to do so, based on its estimation
  of the costs of using the view or not. The view-matching logic is
  reasonably clever, but it does have limits that are pretty easy to hit
  in practice. Even where view matching is successful, the optimizer can
  still be misled by inaccurate cost estimations.