Yeah that's what sucks about these plans. I've been looking to get a smartphone, but there just all these bundled plans with 400+ minutes or 200+ texts and what not. I rarely use more than 100 minutes and 200 texts, but if I want data I'd have to go with a plan that gives me way more than I need.
The closest thing to the European model is Ting, which lets you choose what features you want separately. the only thing is that they run on Sprint (although they do allow voice roaming on Verizon). Aside from that this type of thing is virtually impossible to find. Traditional paygo (not the monthly plans that now dominate prepaid) is the next closest thing to that.