Here's the deal W/dividing by 3. It comes into play after you, the GM, defines magic in his game. SO most of the Lim's will be self-evident. It isn't just a Divide by three and chinse the points on your spells. It's an after the fact point break to allow spell caster to stay around 150 pts (or whatever point limit you set) at creation. IT also makes spells accessible with only a few eps.
So first you create the spell all appropriate advantages and limitations. This is where the GM does it himself or works W/the player, then after all of that is done you divide the real cost by, whatever.
So now 10 games down the road, wihile the fighters are buying levels for theirprimary weapons and thieves are buying DEX levels, the wizards are buying new, better and more powerful spells. So they get the same ramping up as the other characters. So don't take it as a minimaxer's wet dream, but as a liberty offered to GM's to really reflect how they want magic, in magic rich worlds, to work.
Then again if you still don't like it, don't use it.