That's one of the sticking points. 
The OpenRosa specification would not say anything about that. Or do you think it should?
With Collect, the model has always been that users have control over what forms are on their devices. With default settings, there is currently no attempt to fetch the form list until the user explicitly triggers one. We know that in some data collection campaigns, data collectors are trained to perform updates at certain times. That's why in Have Collect exactly match the forms on Central we have described that in Collect, the match would only happen on explicit user action.
However, it's true that in a world where a project manager specifies a form list to be matched exactly, expectations may be that this operation happens automatically. This is in contrast with in the Aggregate world where every data collector sees every form and likely needs to pick and choose relevant ones to download. We could do something like have Collect always perform a form list request the first time that the user has connectivity after the server setting is changed. If the response has the matchExactly attribute, then we could set Collect to periodically poll the server and automatically match the form list. The user could additionally manually trigger the update from Get Blank Form as convenient.