Assume you are a defense lawyer and that you are in trial on felony Theft in the First Degree (theft by taking over $1000). Assume also your client will follow your advice or endorse whatever strategy decisions you make.
The prosecutor has put on solid evidence that your client committed theft. In fact, almost nothing to dispute there. But the state's evidence just barely puts the value of the merchandise over $1000, and you think you've done a pretty good job raising doubts about that. In fact, you think you've been pretty persuasive that the value was worth a mere $990.
The prosecutor doesn't ask for a lesser-included instruction for Theft in the Second Degree. Do you?
On the one hand, people don't like thieves. Some people really don't like thieves. And some of those people will be on your jury. They will want to convict your guy of something rather than let him get away scot-free. If you don't ask for a lesser-included instruction for Theft II, the jury will have to choose between letting him completely off the hook or convicting him of theft, for a $ amount that maybe is a mere $10 more than what he actually took. But you didn't win MJOA on value: a reasonable juror could find he took more than $1000, and if they're motivated to convict of something, it won't be hard for the jurors to find themselves -- in the jury room -- collectively unpersuaded by your arguments.
On the other hand, the jury is given the "acquittal first" instruction. If you assume jurors absolutely and unquestioningly follow the letter of the law, then the jury will acquit or convict of Theft I regardless of whether they think your client is guilty of Theft II. If they aren't convinced beyond a reasonable doubt the merchandise was over $1000, they will acquit of the Theft I. Full stop. Which means acquittal of everything, unless you asked for a Theft II instruction. Nice work, defense lawyer! You just got your client convicted!
Okay, so I framed the examples, and it should be obvious which side I fall on. If your client did something bad, the jury will want to convict him or her of something. But they also like to calibrate their verdict consistent to how badly your client behaved (which is why prosecutors never want jurors to find out what the Measure 11 sentence would be). I think that's human nature, and I'm not all that impressed with anyone's claim that twelve people can apply all of the jury instructions, including the "beyond a reasonable doubt" standard, with perfect objectivity.
All that said, there are other things to consider when making the determination to ask for a lesser-included. If the less-serious offense would still get your client deported, then maybe you want to go for complete acquittal. If your client is facing a Rape III, but he is more afraid of the sex offender registration than the felony, then maybe you don't want to ask for a Contributing lesser-included. (Okay, you'd need weird facts to get that lesser-included instruction, but you get the idea.)
The Oregon Court of Appeals right now agrees with me. (Or I agree with them.) It is important, in some cases, that the jury know that acquittal on one count won't result in total exoneration. The Court is more likely to find bad lawyering, I think, when the greater offense is presumptive prison (or Measure 11) and the lesser-included offense is probation. A common example: if your client pulled the trigger once and missed, and he's got no prior criminal history, it's the rare case where you wouldn't ask for the non-Measure 11 Attempted Assault or Unlawful Use of a Weapon, even if your defense was merely that he fired a warning shot. Another benefit of lesser-included instructions: defense attorneys can use the different crimes to highlight different concepts: how does negligence compare to recklessness, and how do both compare to "extreme indifference?"
In sum, the failure to ask for a lesser-included offense instruction, or the failure of a judge to give it when justified, can be reversible error, either in PCR (the former situation) or on direct appeal (the latter). But the Oregon Supreme Court has granted review to COA cases that say both those things, and so their validity is precarious.
Let's assume the worst: the Oregon Supreme Court holds that, because of the "acquittal first" instruction, and the assumption that the jury will faithfully consider the greater offense before they consider the lesser, it is no longer bad lawyering to fail to ask for a lesser-included instruction, and it's merely harmless error for a judge to fail to give an appropriate lesser-included instruction.
Again, to reach that conclusion, you have to assume that the jury will be so faithful in applying the "acquittal first" instruction that the existence of a lesser-included offense that they might never get to is irrelevant to their determination of culpability on the greater offense
If you believe that, then isn't the defense lawyer committing error by ever asking for a lesser-included instruction? If the OSC holds that the existence of a lesser-included instruction will have zero impact on consideration of the greater offense, then asking for a lesser-included instruction merely invites the jury to convict of something that -- but for the defense lawyer's request -- they never would have had the chance to convict of. If you accept the reasoning that the AG wants the Oregon Supreme Court to adopt, how is that not bad lawyering?