1) Fewer Techniques, More Structure
O Sensei, pruned Daito Ryu techniques way back; Aikido has only a fraction of the number that its parent art does. This makes great sense if what one wants to do is impart principles: you provide only as much detail as you need to in order show how the principles might manifest, but you concentrate on the foundations. I don't know if this is what Ueshiba had in mind, and there certainly are enough techniques to keep me dazzled for a few more decades, but there's little danger of getting lost in minutiae.
After studying other forms of Jujutsu and chin na, I started adding lot's of things to my Aikido. Things that I thought perhaps the founder overlooked. Then when I started seriously looking at Daito Ryu waza I realized that most of the techniques I was adding were in Daito Ryu. That made me ask the same question, why did he "prune back" the techniques. It was only after doing very heavy randori with multiple attackers that I found what I believe to be a reasonable answer- most of the techniques removed were not ideal for dealing with multiple attackers. I found this out the hard way, as when I did multiple attacker heavy randori I wasn't using many of these more involved techniques. Most of the techniques that were removed were to involved, and are only useful when facing one opponent at a time. I believe Ueshiba was streamlining Aikido for multiple attacker situations.
2) Uke Has a Way Out
In brief first-hand experience, and from video's and other sources, it seems that Daito Ryu is all about crushing uke, which makes great sense martially, for why would you want to give your attacker a break? Ueshiba appears to answer that question by asking in turn, " Why hurt somebody if you don't need to?" Tactically, uke might be almost as likely to leave you alone after a survivable throw as after a nasty one. Strategically, uke's relatives and buddies might be less likely to come after you. And at least as important, I believe that human beings have a need, all-to-rarely-expressed, to be kind to one another. Aikido potentially, at least, gives us the opportunity, because its throws tend to allow for less torturous falls. Which brings us to
I also believe much of the leaving a "way out" for Uke comes from a multiple attacker context. Many of Aikido's techniques have a very powerful first blend, if done correctly there is nothing less crushing about Aikido's initial blends than those found in Daito. However, Aikido technique doesn't have the dominating, continuous control found in Daito Ryu. Again if one is always expecting multiple attackers, you don't have time to overly involve yourself with just one attacker. If your initial blend didn't stop them, and you are free to keep moving, then it's likely a good idea to move on. The set up's for more powerful/devastating throws often require you to more fully commit your body to one person. This takes time, and when you're facing multiple attackers you just don't have that time.
There is no doubt that Ueshiba was very interested in multiple attacker situations. For me, asking the question, "how useful is this technique in a multiple attacker situation" cleared up many of my earlier misconceptions about our syllabus.