It seems to me that your main problem is the possibility of accidentally rolling higher on control than you need and getting nothing for that.
With that in mind...
I think that you're ignoring the importance of risk. Having Discipline higher than power makes it unlikely that you'll accidentally take backlash or fallout. Since fallout penalizes spell power, both are pretty darn bad.
Having a chance of overshooting your control roll is the price you pay for not having a chance of undershooting it. That isn't a problem, that's a part of the game's balance.
The extra two points of Discipline that you have when you roll control 2 higher than you need might not be helping you right now, but they're still very useful.
