The importance of the first loss isn't in who died or who affected what - it was the allowance it granted. The actions aside from the battle - this was the original point. Yhwach's goal was never to win the battle but to be present at the appropriate point where every other action was irrelevant.

There were only a couple true goals:

Delay the captains in preventing an all out assault against the soul king Get as many quinces/stern-ritter in soul society prior to Yhwach's absorption Disrupt the natural order and force the Gotei to make otherwise revealing movements (zero squad, the palace, the changing of the commander...)

In a battle, there is usually too much emphasis on a natural connection between the "score" on either side. In Yhwach's case, his goal is radical, and his followers support it in the utmost - blindly as some indicate, as they didn't know their eventual fate until they were blindsided and then shut up by being reconnected to Yhwach.

Look at the chain of events:

• They invade, they tie up soul-society in a ridiculous collection of battles, allowing specific Quincies to position and gather spiritual energy in the midsts of everyone else being distracted.
  • In addition, Ywhach is able to move forward with the capture and indignation of a particular key to his plan: Ishida.
• Broken/Depowered/Failing/Weak/Basically Dead Shinigami who are critical to the defense and survival of Soul Society, are in need of special attention and powerful recovery/repowering/healing/resurrection. This stands particularly true of Byakuya and Ichigo.
• While not necessarily addressed, there can be a few ultimate reasons for the above being important:
  1. Yhwach most likely knew this, and as we now know he always intended/expected/planned on it being Ichigo who killed the soul king, it stands to reason that a fragment of Ywach may not have been able to do this - rather, that he needed Ichigo to have the true blade in order to accomplish this
  2. Yhwach, in activating/absorbing the fragments in his quincy troops would have possibly depowered Ichigo, causing the above to be impossible
  3. In order to have the change, Ichigo had to be introduced and manipulated by the zero squad - one of their defenses is NOT being present (thereby somewhat hiding the palace). By forcing their hand, it exposes them.
  4. In order to perform what they performed for Ichigo, Byakuya, Renji and Rukia, it stands to reason that they had to expel quite a bit of energy. Again, forcing this, it weakens them.

The battles being a distraction is a tactic that Aizen used as well - in the end he didn't really care how powerful the espada got, his goal was to sacrifice enough spiritual energy to overthrow the King. In a way, these plot elements though different in execution are the same in result: Aizen was going to sacrifice Karakura, Yhwach sacrificed his Quincy.

One of the things that I see as a focal point in this arc has been, in similar respects to the Aizen arc, extensively planned over a great many lifetimes. If we take that into consideration, it seems to reason that Yhwach also saw Aizen and Urahara's experiments eventually taking place... and as a result the creation of the hybrid forms. Taking one of the above concepts into mind, I would also see Ichigo as something of a culmination of those eventualities: he is not only a hybrid, he is all three - quincy, shinigami AND hollow. The conditions that ultimately lead to the invasion just seem too much to center on a eventuality of mixed timelines all coming together at a very specific point of weakness, opportunity, and availability of way too many factors.

I'm trying to keep my overall forward thoughts to a minimum as we approach the climax, because I'd rather be surprised than proven right. So I'm just going to leave the speculation towards the past and move on :)