I don't believe most modern "aikido" has "aiki" but relies upon high level jujutsu skills to mimic the "aiki" of Ueshiba.
Speaking for myself (and only myself), this is true. But I'm not sure where high level jujutsu skills end and aiki begins. There probably is no line -- it's possible for somebody to have good aiki skills, but still need to work on the jujutsu, I suppose.
One key component of the difference between jutusu and aiki, from what I can tell from my limited internal strength training so far, is that "aiki" is about using the whole body in a fully coordinated manner. The result of aiki is that those with it are able to respond instantly to unexpected forces from different directions, to exploit those forces for off-balancing the opponent(s), and to generate a lot of power without a lot of movement.