Unfortunately Rasa wasn't as lucky as Mu and Gengetsu with his BT, and got something that barely can call itself "improvement".

"...so especially F2P players get the chance of farming seal scrolls again and giving them a good use instead of forcing them to compete with players that will easily gain cp several times faster than them."

eh... i'm sorry to tell you this but theres no difference when it comes to treasure and event ninjas, in both cases spenders of any kind will have an advantage over free players, because you can obtain seals more easily via recharging (you can even buy them directly). I mean, back in the time whales would just buy seals and get about every ninja from treasures in one go, free players on the other hand had to farm not for months but even for a whole year just to get important ninjas like madara or naruto kcm (back in the time ofc), making seal ninjas relevant again wont do any favor to free players, if something it will make the grind for the meta ninjas even more tedious since most seal ninjas require luck to obtain them (like zetsu for example, theres people i know who hasnt gotten him yet even after pulling edo hashirama from gnw treasure).

If you think really making seal ninjas relevant again will be good for free players you probably already have a lot of time in the game, but remember new players have a very different view on the seal system.