The fact that an instruction on lesser-included offenses is included is not something unique to this case. I have seen charges go to a jury that included everything from the top-count of Murder (a first degree felony), murder with sudden passion (second degree), manslaughter (second degree) and criminally negligent homicide (State Jail Felony).
It would be malpractice for the defense attorney NOT to seek the inclusion and CAN be basis for the verdict to be overturned if the judge disallows the instruction where the evidence COULD have permitted a rational trier of fact (the jury) to have found that the lesser conduct had been proven.
Further, it also generally ensures that at least SOME verdict of guilty will be entered...anyone remember that little trial in Florida not long ago where the State over-charged and wound up with egg on their face when the jury acquitted the defendant? Yeah, I thought you did...