Because it is their job to decide what the facts are. Their answers to those questions actually trump the “guilty” or “not guilty” answers. The judge then applies the law to the facts as determined by the jury.
That is how it is supposed to work.
So if they check off that this was self defense (or rather that the state did not prove it was not self defense), that’s it. None of the other answers they fill in matter. Now, if they determine that the state proved beyond a reasonable doubt that it was not self defense, then the other factual determinations matter.
Sentencing is not a factual determination and does not affect whether a fact has been proven or not, so they are not given that info because it could affect they’re determination of the facts (ie, working backwards and defining the facts to get a desired result instead of based on the evidence). Again, that is how it is supposed to work. It doesn’t alwatlys go that way though.
PS Juries are also called the “trier of fact.”
If these were dealing in facts, they would have already reached a verdict of not guilty.
And juries may determine based upon examining the facts of the cases, that one particular crime was sufficiently heinous as to justify a 20-year prison term, while another was sufficiently minor as that anything beyond a $500 civil penalty would be excessive, even if there was no statutory distinction between the two crimes.
Since judgment of whether a crime was particularly heinous may depend in large measure upon assessments of witness credibility, who else but a jury is really qualified to make such determinations?
If knowing that a particular crime would carry a 20-year prison term would cause a jury to acquit, but the jury would have convicted had the maximum sentence been six months, what that means is that the jury determined that a 20-year prison term would constitute cruel and unusual punishment for the particular criminal act the defendant committed, and applying such a sentence would be illegitimate. Those who seek to keep such information from jurors do so because they want to be able to impose illegitimate sentences.
I should also note, btw, that even from a "factual guilt" standpoint, many crimes do not expressly specify an a minimum level of criminal intent, but in general a major felony conviction should be require a stronger showing of criminal intent than a $200 traffic ticket. If a juror knows that a person committed an action, but did so without significant criminal intent, how should the juror know whether the level of intent is sufficient to justify conviction if the juror doesn't know the magnitude of the charged offense? Sometimes it's obvious, but suppose you were on a jury of someone charged with "Obstruction of an Emergency Vehicle". Is that a $200 traffic ticket or a 20-year felony? One could imagine possible "crimes" meeting such description where the former could be appropriate, and others where the latter would be. If the statute doesn't specify a level of criminal intent, how should a juror know whether an appropriate level has been shown?