I tend to agree. Although as a counterexample for not singing in dub, I present to you Angel Beats. I watched the English dub of that and one particular song that the main singer of a band sings made me cry from how beautiful it was. I’m sure it still would have had an impact, but there’s no way it would have been as strong if they hadn’t dubbed that song. Granted, a large reason for the crying was the episode in general and learning the story of the singer, but it’s so fantastic in English that it seems like that was the only possible way it could be.