Good question Erik et al.. and trust me (says the devil) I don't mind answering. A sincere question, even if you don't agree with the answer, beats the hell out of - well you know what I mean.
First of all skill levels being equal, strength and speed do come into play but there are many ways of resisting an attack besides force. In Virginia last summer (US Nationals) the winner of the Men's Tanto Randori and the Free Style Embu (kata) was Michael McCavish from Honbu Dojo. This is not a coincidence since the two are very closely linked. The best in one are usually very good in the other. Michael by the way is pushing (maybe past) 40 yet he consistently beats the young-uns. The reason is control and experience - weapons he uses real well.
At Honbu far less than 10% of the time is taken up doing randori training exercises. In fact randori itself is usually done after class by those interested. The bulk of the training is kata and basic exercises.
Finally the question of ingrained response. This is something that you must avoid under all training regimes. For those in non-Tomiki dojos examine your training practice and try to determine where this occurs - you will not have to look far. It is part of the over-all mental training to constantly examine yourself for weakness and programmed responses. A knowledge of what randori is and what it is not is intimate to this process.
There are lessons learnt from randori (both training and shiai) that are applicable to the performance of kata and to the application of aikido and conversly lessons learnt during kata performance that are applied to randori. Nothing works in isolation. If however you were to ask me where I obtained most of my self defence skills it is through the Koryu Goshin no Kata (Old style self defence) which contain some absolutely brutal techniques. The level of understanding of the kata (I like to think I manage OK) was indeed made possible through randori practice.