I think a lot of skills need to scale non linearly with getting the majority of it in the first 50-60 points or so and the last points should give different bonuses like the above in certain intervals to award putting more than the minimum.
I capped my meditation at 30 cause if I got time to sit and rest I don't care how long it takes (sorta). I don't see any need to put it more than this... maybe even just take away these points too in the future.
meh, if you have vitalism you get meditation capped to your skill bonus unlocked anyway. So its not like you dont gain any mana from the action of resting as long as you have enough vitalism.