On your side of the argument, it is easily feasible to be disappointed. For the longest time I remember that Kirin only was pullable through frags. This was also stated by Oasis moderators as well. I guess in the past he could've been viewed as obtainable through the same methods of Susanoo Itachi. Hence the reason they put that summon in events. It was understood that KOH was an exclusive pullable 2k scrolls summon. I'm not sure when they decided to make Kirin a full summon in the treasure but this must've been an update dealing with 3.0

Now, on the flip side of this argument, I would never purchase anything obtainable through shop coins. That's just me personally. Sure Kirin has one of the sickest animations and rarest chases, but ingame currency deterred me from that purchase altogether. Am I saying you spent your money improperly? Not t all. You make it, so spend it as you will. I always preach to my group or other people who spend, that you have to have patience in this game. I don't know much about Chinese seals and summons so I will leave it out of this. Spending though you have to always consider why a business does what it does. Susanoo Itachi for the longest was obtainable through sheer luck of the slot machine and crossing fingers hoping you get 2 frags in treasures. Now he is obtainable through feast wheel at almost half off of his original price point or more. Granted it is ingot only frag purchase but for those who did buy seal scrolls to get him were screwed like a pooch. I bought Mabui and she was released a couple months later as a COMMON. I was torn and may have easily been the dumbest purchase I've ever made in this game lol. My thing is, this game is always changing. Having things early is exciting but not always worth it.

Solutions:

Add an optional choice of a super rare-This could be applied to both seals and summons. This should only happen if you have the the respective ninjas or summons tht are supers so you don't end up with a dupe.

Provide more points and frags- I feel like if you double up on a super rare it should be more rewarding. The baseline 4000 is unacceptable to be honest. It should consist of a 25% increase on the store price as summon points receivable.

Transparency-Not many people are aware that he is pullable. If you do have knowledge of this, Kirin is still one of the rarer pulls between him/her and KOH.