Looks like the keyboard layout is an attempt to help identify the key columns more easily. The "V" shape vertically divides the keyboard into two sections both visually and by touch. This may help in locating the desired function quicker. Also, by alligning the keys in an angle, the width of the keyboard would be slightly reduced but with an increased length. I suppose it is easier to move the fingers vertically than horizontally - as further evidenced by the traditional more rows than columns keyboard designs.
I own an HP-48S and have been waiting for a more ideal calculator. i.e. one that is much smaller and can do STO and RCL with a minimum number of single finger keystrokes as the 41CX gave us. The darn HP-48 series forces you to "create" variables even for those times when you just want to store a number in a register (i.e. a global one that does not care which directory you are in and does not require a manual garbage collection). Having to write a program to do this basic capability is a shame. My ideal calculator is a thinner HP-41 with an updated display and faster processor (with all the functionality of a HP-16C built in). The 33S is close but I need to witness its look and feel in real life to tell.