On this forum and at seminars, I have often hear from a segment of the Aikido community that does not believe that self-defense is necessary. Besides, if one does include it, that it can't really be used against someone whose is trained or street experienced (some thugs really are) or it seems implied that if one does have that as a point of emphasis that you somehow forsake it as a means of self-improvement to become a better human being, marriage counseling, working with troubled youth and just plain having fun! It would seem that there is this fork in the training road that its either martial and that's all one can focus on or its the softer side of self-improvement and metaphorical uses. I still have yet to hear a convincing argument on why one can't and shouldn't have both sides as parts of one's training path. To be sure, " realistic" is subjective and is an approximation on a continuum.
I have much respect for your point of view, and I too would like to believe that there is a "middle way." I also see wisdom in the observation that people who don't train against seriously committed attacks may be ill-prepared to defend them. Speaking on behalf of fellow (pre-dan) klutzes, however, I sometimes feel in aikido technique classes that I'm treading water simply in trying to follow all the mechanics of what the teacher is teaching. Making uke into a 200 pound gorilla who is genuinely trying to break nage's arm (or nage's neck) may be crucial for improving practical skill, given a nage who already has a fundamental grasp of the mechanics. In my case, though, I am not convinced it would help to me to achieve better clarity in comprehending technique.
Most of the practical defensive instruction I've experienced in aikido has focused more on movement and alignment and blending against the rampaging gorilla, rather than trying to execute specific techniques. Sensei is always careful to point out the atemi possibilities, as well as the aikido techniques, that open up once given correct positioning in concert with attacker. The former tend to offer options for a karate-style response, even assuming that one misses or screws up an aikido technique that could otherwise be a good fit.