I think we need to first clarify what the initial article is talking about precisely. It appears that Abbe Sensei is referring to "Early" Aikido as being defined by effective technique. i.e. technique that works regardless of how compliant or uncompliant the subject of the technique (Uke or Attacker) is being.
Modern Aikido in this case would be defined as Aikido that would only work in the dojo with compliant Uke who have been programmed to respond in a certain manner to the slightest of movements, whether those movements truly affect their mind/body or not, hence the use of the word "dancing".
In this light if one's Aikido appears to be soft (slow, round, fluid movements etc.) but it has the required martial efficacy then such waza may not fall into the category of "Modern" aikido as per the article. As said before, "soft" Aikido can be Early Aikido if it is a martially effective Aikido. So although the thread has moved onto a hard vs soft argument, the initial article merely used soft to describe aspects of training, not the expression of technique per se. Aikido is expressed in a hard or soft manner depending on the nature of the environment and the conflict to be resolved. Although one's waza may become visibly softer as one develops it does not mean that the waza has lost any of its martial utility. I think this is what Abbe may be referring to. Soft from my impression of the article refers to Aikido that could not work in a serious martial or self defence context with resistant opponent.
I had a lot of fear fueled adrenaline going and this gave me the speed and power that I do not need or use on the mat in an aikido class.
Kim's story above shows another dynamic that can be used to compare the "Early" methods and the "Modern" methods also, that of Adrenal Stress Responses. Her adrenal response allowed her to generate more power and speed than she would usually generate in class, which means that typical class training may not create a high enough threat level to generate the "fear-fueled adrenaline" response. This is important because Adrenal responses do not always have the effect that Kim experienced but can do quite the opposite, causing the Freeze response where one simply shuts down mentally and physically in a fear-gripped panic. Kim gives an example of positive adrenal response, the one I gave (Freezing) is an example of negative adrenal response, iow one that can hurt your chances of survival.
Early Aikido training as per the original Abbe article may have maintained a regular martial edge that would often bring one to a place where enough of a threat was perceived to activate an adrenal response (whether positive or negative). This would aid in training the individual to control these psycho-chemical reactions and utilize them for a positive outcome as seen in Kim's case. The absence if this sort of edge as may be seen in Modern training (as per the article's indication of such) would mean that dealing with adrenal stress may never be entered upon at all in trraining since the martial danger of the attacks themselves may be mitigated to allow for a more smooth, free flowing sort of practice where the student in fact never feels in danger or threatened by the attack of one's partner.
Just my 5 cents.