This article lists many examples of using ものだ to articulate "deep concern." The author of this article explains that when you connect words which indicate desire like …たい and 欲しい with ものだ, your speech indicates hope with some concerns.
For instance:
「次の大統領は優秀な人になってもらいたい（もんだ / ものだ）。」
Translated as: As for the next president, [I] would like a prominent person to be elected.
The nuance in this sentence was explained as "The current one (president) isn’t good, so you’re expecting the next one with frustration.”
「こういう服を一度着てみたい（もんだ / ものだ）。」
I] want to try to wear clothing like this once [in my life]. *You long for wearing it, but are resigned to wear it at the same time.
Earlier in the article the author explains that "the combination between predicates and ものだ or ことだ determines the nuances. When you connect words which indicate change of things or people with ものだ, your speech indicates inexpressible deep emotion. In general, the emotion is not expressively told. You need to guess it."
Does this explanation explain why combinations of words linked to desire combined with ものだ automatically signal concern within hope? I'm a little confused about why concern is the thing that is signaled in this kind of construction.
