K-Man, I totally agree with the thought of, "Wow, this feels easy and smooth.... not at all like (insert time frame a few years back)." My second main aikido instructor told me about 15 years or so ago, "Ah, you've got that BTDT look now, good."
So I asked him, "BTDT," and of course he replied, "Been There, Done That."
One thing that causes fear automatically is fear of the unknown, it's almost more guaranteed to cause the fight/flight adrenaline reaction than things with big, gnashy teeth. Once you've spent a few hundred hours actually doing randori, or sparring, or ring work, or whatever you call it in your style, you've probably seen or felt 99% of the things that can happen to you, so there is very little left to be discovered. That's not to say you won't get surprised, but you've also learned that being surprised on the mat isn't so bad. It applies to Drop Bear's stated issues with Judo, definitely. My first 10 years in judo were a constant reminder of, OK, nneed to work on that some more.... but the steady accretion of knowledge accumulated over those same years caused less and less instances of surprise, and more and more of understanding. It comes, as students, I'd say that in the beginning we're all impatient.
One thing to consider... I was talking with a guy who trains divers, the kind who jump off platforms and diving boards and do the flips/twists as they enter the water, not that that see how far down they ccan go.
He told me that there's a general range of times of repetitions for muscle memory to be grooved and unconscious, i.e. "mastered." His word, unfortunately loaded with other meanings in the MA world. But still, applicable. The number, generally, is 10,000 repetitions for a movement to be automatic, and grooved nto muscle memory and coordination systems. Really great atheletes have a lower number, but hardly ever below 7,000 reps, and those of us who are more clumsy might need as many as 12K to 15K reps, but it does get there.
Think about the time frames involved to get 10,000 reps of a certain punch, or even a jumping, spinning kick.... versus how long it will take the partner-training grappling art person (pick one, aikido, judo, wrestling, sticky hands, BJJ whatever) to be able to get 10,000 reps in on something?
Say it's the shomenuchi ikkyo above... how many years of training? Thanks to K-man, I'd say the time frame for a dedicated student with presumably above-average athleticism and stick-to-itiveness (I'm assuming that's K-man) gets to 10,000 reps in 7 years.....
In my opinion, THAT is why aikido (and Judo, Drop Bear) is hard. It takes a lot longer to get the required reps in. Do this analysis... time how long it takes you and your partner to work through a single technique from aikido. Include the set-up time, as that is included in your "rep" time. Then, compare that witht he tim it takes you to practice a basic reverse punch. How much quicker to get to 10K reps on the reverse punch? How much quicker to have that mastered?
There you go. There is the reason for the difficulty. My opinion, of course.