The point of having to pay for the higher rating is that if you don't, you'll run into the people who'll buy magic up to 2, get implants, pay 10 karma to buy it back to 2, buy more implants, rinse and repeat.
And the issue here is?
Player starts with a magic of 1.
Buys magic to 2
Takes one point of implants.
Magic and Magic max drop by one (1/5)
Buys magic to 2
Takes a point of implants
Magic and Magic max drop by one (1/4)
Buys magic to 2
Takes a point of implants
Magic and Magic max drop by one (1/3)
Buys magic to 2
Takes a point of implants
Magic and max drop by one (1/2)
Buys magic to 2
End result = Magic of 2 (which is only a step above being useless and is currently capped), 50 karma spent, and four points of ware.