the main issue of BA rank 7+ right now is that is simply not worth to go for it until you bought all the cloths available, until you got level 9 charms on all the items in move 1 and 2 and level 7 in move 3 and 4, until you reach page 18 in myoboku cultivation, until you reach level 7 in all the summons in summon cultivation, until your tactics got to level 7 and until you got treasure tools for move 1 and 2 with 6 level 14+ besetted essences. At that point, and only at that point, you may begin to think about going for rank 7 BA. That's how useful is right now that feature for coupons spent/power ratio efficiency.

Moreover, as soon as we get another new cloth or another new feature those things immediately are more appealing than BA rank 7, to not talk about 8 if not 9...

He's saying it's better to spend on other items that give power before increase battle armor rank 7+ since the spending required to level the battle armor costs a lot more if you were level something else. For example: I know this is random number and might be wrong but let's say it requires 10k coupons to level rank 7 to rank 8, that 10k could be used else where and might give you more power if you were to increase the battle armor rank.

Currently in China, they have the shops combined into a new type of shop that has power items and yes you c*e the coins to buy them. To earn these coins, you just have to do all of the dailies.

Like I said in my second point, there will be an update to the shop and you will be able to buy advance threads. If you want more information, search in youtube and use terms like naruto online china (Memo has a video on the shop update) to find videos of this.