Striking at a very basic level is fundamental to martial arts, but if there is anything you can't accomplish with a single, strong, balanced attack, you are either:
a) using the wrong tool
b) in a fight you have the option of not being in
The martial traditions from which Aikido is descended assume a generalized tool, and assume that b) is not the case.
The essential problem with getting too fancy with your striking and grappling when practicing Aikido is that you are no longer training for a life-or-death situation that came out of nowhere that you are trying to survive with limited information as to what is really going on.
Which is not to say you shouldn't do it at all, it is just not something that your regular general Aikido training should focus on.
All Aikidoka should learn to deliver a single, balanced attack to whatever part of another human body they choose, using anywhere from 0 to 100% of the force they can muster with their entire being. You have to work at this but it isn't rocket science (or even sweet science).
Aside from that, I tend to believe that the strikes that nage might do while performing a technique are just pugilistic sugar.
My feeling on training to land a single, balanced attack is that it only ends up being useful in a strictly kata situation. If you look at the top boxers - only the really top guys have a connect rate over 40%, for most boxers (even good ones) the connect rate is much lower. If you rely on that one attack then you've got less chance of connecting then if you just flipped a coin.
It works the same if you're giving or receiving - if you only work against that single balanced attack then you're training yourself to work against something that really doesn't happen very often.
Fine for Kata training of course.
In terms of the mechanics - I feel strongly that strikes have to come out of the same basic body usage as everything else.