You have said that there is no "better" or "worse" when it comes to wanted lives, regardless of physical or mental "impairment." And you have said that these lives are totally equal (I agree with you on this, by the way). However, when taken to an extreme, it could be inferred from your argument that you would find a rabbit (who very much enjoys being a rabbit) to be just as important as a conscious, intelligent human.... If you do not agree with this, would you be able to provide the "cut-off" at which one wanted life becomes more important than another?
What I tend to say is that "better" or "worse" are terms in respect to particular ends (among others) and held by particular people (among others).
What I tend to say, further, is that there is no neutral, cost-free, universal "better" or "worse" lifeway, and so I insist that such assertions of value be situated in their history, circumstances, aspirations so that their stakes are revealed rather than disavowed.
I have no problem with such assertions of value -- quite the contrary, in fact -- but I have enormous problems with refusals to take responsibility for such assertions, refusals to recognize their costs (there are always costs), refusals to own up to them.
I must say that your comment about the rabbit is enormously perplexing to me. To whom is the rabbit's life presumably "important" or not in the desired assertion? The rabbit? A lab technician preparing to test a drug dose on the rabbit (something I might or might not approve of, by the way)? A child for whom the rabbit is a companion? I doubt I would see the importance of the rabbit's life as a vegetarian and as a non-hungry person in the same way in every instance as a carnivore would or a starving person, for instance.
If you are pointing out, then, that I seem to resist the assumption of some "god's"-eye perspective (that phrase, like the phrase "playing god" which is also regularly trotted out in discussions like this, is meaningless, strictly speaking, and obfuscatory) from which to "survey" the multiform scene of liveforms and lifeways and allocate to them "objective" values in a hierarchical scale of "importance" (to what? for what? to whom?), well, certainly that's true.
But those who pretend to do this are deeply confused in my view, and in more ways than one, and all too often, much worse, are up to no good: likely scamming after priestly authority.
In bioethical contexts, I argue that a non-lethal actually wanted lifeway facilitated, maintained, or arrived at through informed nonduressed consensual recourse to (or refraining from) actually-available technique, whether normalizing or not, is all the "cut-off" we need.
Where lifeways are wanted and consented to but seem to us irrational or hateful or what have you this might mobilize efforts to educate and convince, but should not mobilize the police unless the wanted lifeway represents a palpable threat of harm to others -- where "harm" is considerably more than some so-called violation of "dignity" or "nature" or "decorum" as indicated by the discomfort of a social or religious conservatives in the presence of a difference they have a distaste for.
By way of conclusion, I will note, as an entirely personal matter, that I find rabbits boring and dumb and considerably less cute than one would hope given the hype.