, Blood+ ain't supposed to be an ecchi or hentai genre type. this also applies for the other characters by the way, safe for a few others that i couldn't mention.
Same for Blood-C, even tho the art style of it made Saya look hot, but that's just CLAMP's art style, Saya wouldn't look like that if she were in live action. she could still be beautiful, cute and gorgeous, but not sexy or hot like some anime females. Take notes from Blood+'s Saya for example, she isn't hot or attractive with big boobs and stuff, but she's still cute and gorgeous nevertheless.