I would have waited until after the Castro brothers were dead and buried. As it is, it looks like a surrender.
Well, no.
Well, yes. Appearances matter in foreign policy. These sanctions (unlike others) were rather personalized around one individual, unfortunately. As long as he remains alive, he (and his brother, by extension) can claim victory by having outlived them. As if we had simply given up, acknowledging failure. Which is what essentially President Obama has done here.
I'm not sure how that sort of rhetoric applies to the actual situation. Certainly not in your lifetime has Cuba ever presented some kind of threat, imminent or otherwise to the safety of the US. If the original goal of the embargo has become irrelevant and it remains in place out of tradition and/or personalized spite more than anything else ... it's hardly a "surrender." Someone has to clean up these kinds of mistakes, after all. If not Obama, who?