no, Obito shouldn't blame Kakashi for Rin's death. they are shinobi, people get killed! (heck, people get killed in this world too) unless Kakashi personally killed Rin, he is not responsible for her death. how about she is responsible for her death, as a totally hypothetical option, and if she were stronger she wouldn't need Kakashi to protect her........
(also, what the guy above me wrote. Obito is blaming reality)