SP Reseter NPCs working after obtaining Master Class

I'm sure we all noticed how even though we would have our Master Class there would be SP Reset NPCs in further maps (ending with the 60 lvl cap map), and how stupid it was that NTL put them in later in the first place when they were useless. Instead, why don't we have them be able to still do their job but instead of resetting your basic class SP they would only reset your Master Class SP. That way we can experiment with different options with the Master Class we picked and still give the Reset Books a purpose. Obviously this would require a large sum of zeni as you level up so you would need to use them wisely.