Only if your index finger doesn't work. I actually prefer the top-scroll control. It means I don't have to comprimise my grip on the body (move my thumb) to operate the scroll wheel. When I have my 70-200 F/2.8L hung off the front, a good grip is necessary to keep almost a grand worth of glass from taking an unscheduled vertical excursion.
The rear scroll wheel cameras still have the finger wheel, it operates the same as the rebel finger wheel. The thumb wheel operates like the rebel finger wheel does when you are pushing the exposure button (with your thumb). It also takes the role of the rebel's directional buttons.
I suppose if you were in the habit of not using your left hand when shooting with your 5-lb lens you might have a point. . .
*except* you can't recreate the function of the rear scroll wheel on your rebel without moving
your thumb, either.
Plus the rear-wheel cameras tend to have beefy grips.
So, for example, in manual mode, the finger wheel adjusts the shutter speed and the thumb wheel adjusts aperture. Or in Aperture Priority and Shutter Priority modes, the finger wheel adjusts the priority component and the thumb wheel adjust exposure compensation.
I recently traded a 2-year-old rebel with kit lens + $100 for a 4-year-old 50D body just to get the extra controls and I am very happy with that decision. I shoot full manual now most of the time, with back-button focus and spot metering. I'm pretty fast and getting faster.
I can still pick up a rebel and work it, but it's like typing on your phone vs typing on a real keyboard.