I do agree gaming could be (alot) better. ATM I resort to using things like Battleping to get around it which slashes my international latency in half showing just how good things could be for gaming if it was bumped up a bit on the priorities. That said, things have been this way in SA since the dawn of ADSL. Gaming has always been very low on protocol priorities, way down there with torrents which is why there are local gaming VPNs/proxies. Considering how games are the most time critical applications on the internet, being such low priority is just going to ruin the experience.
From a technical standpoint, there's no reason why it couldn't be done. Popular games use a limited list of ports/IPs that is not difficult to maintain. Game traffic is also very low (10mb per hour/2 hours), far less than that of HTTP/Email, the traffic is a lot more time critical though. Not only that, time spent gaming, is time NOT spent torrenting, so overall monthly usage gets lowered. Basically ISPs can deliver a great gaming experience at little to no cost on their end if they want to. HOWEVER, from a business standpoint it makes sense to keep gaming very low priority as it creates a need for the much more expensive unshaped capped accounts. Nobody uses those accounts for torrents, they are too expensive per gig, they get used for gaming and gamers will pay the price as they need the higher priority before things become usable.
As I said though, its been this way since the dawn of ADSL in SA and almost every ISP is guilty. It would be great to see it rectified on the Mweb uncapped accounts, as that would really make them the ultimate all round accounts, but its unlikely.