As a gigantic fwiw...
A while back a fella came and visited a class I was in. Yudansha level. The instructor demonstrated a very simple Munetsuki Kotegaeshi (for the newbs: wrist turn from a thrust punch to the chest). The fella comes over, bows to me, then he stands back a few feet and starts to kinda throw his body forward while delivering a kind of floppy, arm turned, "prebent" wrist punch while "hopping" forward on his forward foot. I stepped aside, got my hands up, and then just watched him hop past me. I never got to the kotegaeshi part because a) I had no idea what the heck he was doing and b) since he was a visitor I was trying to be polite and not say "what the hell was that?".
So he turns and asks why I didn't do the technique. My reply (which came out before I could self-censor) was that I was waiting to see if he was going to fall down by himself. He just said he was trying to give me a good, blending punch for the technique. So I bowed and we did it again. Yes, this time I threw him. And yes, all I had to do was do was kinda be in the right area and move a bit and the fella flew like he had a rocket strapped to his butt.
That was a really extreme experience. There are folk doing the other extreme as well -- same technique but they'll deliver a punch that is essentially a standing strike with zero attempt to actually hit anything. They are more focused on being totally stable and basically a sack of rocks. They don't reach you, they don't commit, and they are like throwing a sack of rocks.
I sometimes think of the guys who take the running start and are up on their toes ready to fly before they even contact as "uke-o-matics". They've gotten so good at taking ukemi (in the sense of flying) that they no longer attack. They're ready to fall before they've delivered anything at all. So they've become complicit in nage's work rather than giving nage something energetic and committed to unravel.
That said it is always a difficult balancing act. You can be a sack of rocks and be just as useless on the other side of the spectrum. Or you can do spectacular stuff without allowing nage to actually do anything.
But I know what you're saying. My personal pet peeve is seeing guys take ukemi who have that bobble-head style. The moment anyone touches them their head snaps around and they look like a spastic gumby being thrown around. Now there are people who *can* do that to a focused attacker, but some people you see just take it to an extreme in their ukemi.
Anyway, at some point a balancing act if found between a "good" attack and "good" ukemi. Some just focus a *lot* more on the ukemi and having the attacker blending as well. Which is great if you're being attacked by an Aikido practitioner. Not so great if it's the big P-O'ed guy at the bar...
Final word of advice -- worry about what your sensei is teaching you and not what you see on youtube. Youtube is the great equalizer -- you have everything from a few snippets of really good stuff to virtual landfills worth of total crap. The great thing about youtube is that anyone can video tape themselves. The worst thing about youtube is that anyone can tape themselves.