While I personally wish our men in blue to be fully kitted out, it's not practical. Rifles are expensive, require better training and are far more intimidating to your general public. Can you imagine seeimg every single officer walking around like a self contained swat unit?
If they were patrolling high risk areas like townships or even central Pinetown, then yah, maybe, having heavier fire power in the van makes sense but that was a relatively quiet suburb. Also, it's a van, not a close vehicle, so it only has the front seat and the lock up section, where are they going to store all that gear securely? To physically carry it all shift is exhausting and to leave it in the van while attending a call is high risk in this country.
These officers were great at what they did, with the resources they have. They were most likely first on scene on had already called in for other units who would be coming loaded for bear but they had to either contain or delay these perps and all they had was their standard gear.