No, that just demonstrates the limit of your understanding. What I'm describing does not imply anything "wildly unethical" or in an "unreasonable way", and it most definitely happens.
We're not talking about jurors getting pissy and deciding to let a killer walk just to punish the prosecution, which is what you seem to be implying. We're talking about jurors who are opened up to an unconscious sympathy for the defendant (slight as it may be) if the defense can believably argue that the prosecution is on a fishing expedition with multiple contradictory charges because they're not even sure of their own case.
It's a nudge, not a bludgeon. It's not a lack of ethics on the part of the jurors, it's the presence of empathy that the defense can play off of to try to instill doubt.
Jury cases are very, very much about how well you can play the jury, in addition to the facts themselves.
Because it's not necessary, except to feed some bystander's need for a worse-sounding charge, regardless of the actual sentencing.
It might be different if we were talking about the difference between a sentence of 2 to 4 years with Man2 or 10 to life with Murder2.
But we're not, and you seem categorically incapable of processing that fact.