It appears that you equate treating every encounter on the training mat as potential death as the only way to acheive one's full potential.
I can say that I train seriously and w/ focus but my mindset never believes that my training partner is going to kill me; in fact, I purposely aim to cultivate other forms of feeling and intent within myself in order to manifest the best technique I'm capable of.
Definitely a case of YMMV.
I personally believe that Uke is as much of an Aikidoka as Nage is. They aren't hunks of meat that mindlessly attack and idiotically get thrown. There is a lot more dignity to the position than that in my opinion. A morotedori done effectively should control and take nage's ballance. Frankly, that's the type of energy that make techniques fun and challenge nage to study hard. Ukemi is an art form in my opinion. I was told once that there is not an Aikidoka alive that isn't, or once was, a better nage than uke. They told me that you will struggle with nage so long as your ukemi art is sub-par.
I don't necessarily take the mind-set that my uke is going to try and kill me, but I do view them as competent, and a challenge. I mean these are some of my closest friends LOL, it's hard to view them as murderous idiots. I view them as a challenge to my nage. and, I view my nage as a challenge to my ukemi. It is a bit incestuous.