Hello,
Unfortunately, some of these questions are well outside the scope of my ability to answer. While I recognize that the shops/methods for getting some ninjas are pretty different between this version and the CN version, the answer to why effectively boils down to "because the devs wanted to do it this way." We *do* have plenty of shops that allow direct spending of ingots (though not every week, and as you said, some are worse than others), such as Shinobi Feast and Konoha Special Sales, but the options for direct purchase of ninjas are more limited in EN.

That said, I can put in a suggestion for you for us to pick up some of these shops, if you'd like me to do that.

OK, I see now. Yes, I can put that in for you, too. Sorry about the lack of easy ingot spending opportunities this week. For what it's worth you aren't the first person I've heard this complaint from, so I'll make sure that feedback goes in.
Thanks and have a great day!