there are several good reason to wristmount, these are just my own thoughts and feelings.
I like having my computer/deapthgauge on my wrist for the following reasons.
its easily visible
and on decents and ascents where you can see basically NOTHING or have no references its very good to have the computer on the arm, where you still can hold on to your buddy with one arm and still have sight of your computer and have control of your BCD.
in sweden where sight in water can range from very little to good
10 cm - 15 meter
(I have been diving when you cant see past your own shoulder)
Sometimes you have to go down and pass through a watershift wich might be 5-20 meters in deapth to get down to crystal clear conditions
it is there infront of my face with no effort made, no having to "get" it its just there
it suits my diving style (like to go "skydive" to the bottom)
a small turn on the head and the computer is in sight and not occupying a hand, no other movement neccesary
.
personally I prefer not to use a computer who is air integrated (normally they are console mounted) for many reasons
1 all instruments in one package, if it breaks you are freash out of instruments (not counting backup instr.)
2 my manometer is battery operated ? no thanx !!!
3 harder for your buddy to see (exact angle on lcd display, all I am ever interested in is my buddys air supply reason for this is that he will have control of his computer and we do have a dive schematic wich we will follow...
4 I prefer to spend money on "better" things such as better gloves or fins or a better mask.
I do in no way say that a console mounting is a bad idea, or the cobra computer is a bad choise, its a good computer but neither of it fits my diving style. ie just a personal choise.
dive safe