If you are comfortable with territory-scoring, you should think of the situation as “scoring a point of territory inside the ko”. That would be, black getting the central “3-3” intersection in your picture as extra territory when winning the ko.
Let’s ignore area scoring for now, and imagine we play by territory-scoring rules (you can think we are using Lasker-Maas rules, or AGA-rules and counting territory for example, or maybe “Japanese rules of a different hypothetical universe”).
Normally, there are many trully neutral non-ko-threat dame in the board, say like 8-12 dame maybe (really depends on the type of game, like big moyo vs many fights etc). The last ko is fought before filling those dame, it is obviously more valuable than just dame. Often, you will not win this final ko-fight having lots and lots of extra ko-threats, but barely win it, maybe you will have just 1-2 extra ko threats compared to your opponent. So, the situation will be that you take the ko, your opponent fills a dame (he might pass but what for? playing dame is at least as good, maybe he gets to win the ko somehow by keeping playing instead of passing. A proper full game includes dame filling ). Now you might fill the ko and that’s it, you win it, you get the “last prisoner” you captured, but nothing else. You might fill a dame just to “show off”, because you know you still have one more ko threat. But if your opponent keeps filling dame, you can’t “show off” forever: you will HAVE to fill the ko, or else lose it (and your opponent might just fill it and complete it, not wanting to “show off”. You now lost the point of that “last prisoner” in the sequence of ko-captures).
Now, imagine the same situation I just described, but there is no dame, or very little dame compared to your ko-threats. Now you make the ko-capture, your opponent has no ko-threat… and there is NO dame! So, he HAS to pass (if he does not, he fills his own territory, losing a point… that is no better). Since he passed, you pass, to finish the game by two-consecutive passes. WOW! The ko is still open! You did not “fill” the ko! But you could do this because you had so many ko threats, that you managed to keep the ko open even until all dame were filled, and your opponent could do nothing, not even dame, other than fill his own territory and pass… so you pass to.
In this hypothetical situation… Don’t you actually deserve the extra point of territory of the unfilled ko intersection? You clearly controlled it, you had enough ko threats to keep it open!
Well, this is “the actual reason” behind the scenes for this fight: you are fighting for this extra point of territory! Lasker-Maas rules and AGA-rules when counting territory (with pass-stones) give you this extra point: since your opponent passes, he gives you a pass-tone, but THEN you can fill the ko instead of passing, so then your opponent has to pass AGAIN. The extra passing-stone that he gives you effectively works exactly the same as if you could just pass and reclaim this extra territory point.
Under chinese rules, the effect is basically the same because you just “fill” the ko, which is now YOUR territory, and it has no cost! Filling your own territory AFTER all dame are already filled, does not change the score in area-scoring rules (if you do it before ALL dames are filled, you DO lose points: as you are just territory-filling for a net +0 score, while your opponent fills a dame, for a net +1 score. It is just like japanese! you lost one point for prematurely filling your own territory!). So, under chinese rules, it works just as if you could count the ko-intersection as your territory, for one extra point if you manage to not only win the ko, but also leave the ko open until all dames are filled.
So, it seems that these fight makes sense in territory and area scoring rules, this is not a difference of area vs territory, but whether this last “ko intersection” territory can be counted or not. What do the Japanese rules say?
Well, this was a famous rules dispute involving Go Seigen twice. The Japanese ruled against Go Seigen BOTH times, even though Go’s position in the dispute was reversed each time! It seems that the rule at the time was actually “Go Seigen loses the point”. Rule disputes involving Go Seigen at Sensei's Library
Modern Japanese rules says that you CAN’T reclaim this extra territory point, even if you have an infinite number of Ko-threats. You just have to fill it, it is mandatory, sorry. So this is the real reason why there is no “dame-fight” in Japanese rules but there is in Chinese-Rules (and other chinese-like territory definitions, like that of Lasker-Maas territory rules).