Using the parameters I listed, the 20th level fighter focusing on his sword skills (or archer focusing on his bow) would have:
Old Method - 63 ranks = 126 DP spent = +113 bonus
Proposed - 200 ranks = 100 DP spent = +200 bonus
The proposed method is far simpler to calculate, continues to encourage development, and allows for high level bonus results for characters who really stick with their favorite skills.
Now when you say, yes you can fire 3 arrows at the same time, but each one after the first adds a -20 penalty to all (therefore 3 means -40 on all 3 shots) and firing at 3 different targets means again -20 penalty for each target after the first (another -40 for all 3 shots), and rapid draw/load (-20 for each arrow beyond the first) = -40, and load and fire in the same round = -20....
-40-40-40-20 = -140..... For that 20th level character, he now has a +60 bonus on his quick draw, three target, three arrow shots. Each shot still resolves independently.
Even the 1st level archer can try it, but at first level he's only got a +10 bonus, so unless he way open ends on all 3, he doesn't stand a chance.