Not Really. The main reason for this is explained below:
When you roll down the rear window, It goes inside the door covering but due to the wheel arches, Its movement to complete bottom is restricted.
If you carefully observe in some other hatches, Maruti 800 for instance or even a sedan. Their rear glass completely rolls down. Why? Look at the picture below:
The car has a quarter glass, So the area which will be occupied by roll down glass once you open windows wont be obstructed by wheel arches, hence glass fully disappears after rolling down.
Let me add my bit.
What Vibhor said is exactly correct.
Full glass drop is affected by the wheel arch ... this can be avoided by either the M800 solution, so well illustrated by Vibhor again, or by using a sash with some area of opaqueness. This is the approach used in the Alto or the Figo etc. In this approach, if you want a full glass drop, you will need to have a larger area of 'black', but mostly, manufacturers compromise, and minimize the 'black' by letting the glass stay up maybe a couple of inches from full drop.
A very inventive approach to this problem in marketing is to say that this is a safety feature, if the rear glass does not drop fully, the chances of a kid leaning out (or falling out!!) or even throwing something out of the window are minimized.
Regarding the Door Beams being a factor in this, I would say no. Unless the design of the car is very very bad, you can always avoid the interference of the door beam with the glass travel. It is only a matter of ensuring the proper stack-up of all the parts in the depth of the door.
Additionally, if that were the case, we would have the same problem in the front doors too, would we not??