I'm not really a Vodacom fan but I have to admit, I can see a use for that R2000 unlimited data option.
Example: you live in an area that doesn't have ADSL, you could get by with using your phone as a wifi hotspot, which would save you the R1100++ you would have to spend anyway to get the higher speed uncapped ADSL options.
And you get unlimited calls as well.
Combine that with the possibility of getting multiple SIM cards attached to a single number and you could potentially have all your devices running off that one contract, like a phone, tablet and router for example (I am assuming there are no special clauses attached to disallow this)
I hope Cell C comes up with something similar.