Hello,
In regards to Ashura, rest assured that his price will drop as time goes on.
In regards to the seal scroll drawings and recruitment, I can make that suggestion for you, but I'm pretty sure that the game will not deviate from the Chinese version in that regard, so what seal scroll treasures we will get will not likely change in that nature.
In regards to SSP Naruto, his price has actually already dropped substantially from his original release price (to something like 60% of his original price). He's also already a pretty frequent ninja in events, to the point that many players complain about him being pretty frequent, so I'm not sure how much more frequently he could be present in events.

Thanks, and hope this helps!