I'd love to see the same game from other peoples' perspectives...
you can get great speeds with a 3G dongle or on a phone, but the problem as I said before is when a competing signal comes into play and your connection jumps from one mast to another, or your signal suddenly downgrades. The biggest issue as I see it, is not whether it is feasible as a technology for gaming multiplayer - its clearly very feasible -- the problem is that it is inconsistent and everyone has a different provider, they're on different plans, and they're in different locations, with varying access to different masts, allowing different signals, resulting in different speeds. Allowing such inconsistency into your multiplayer eco system leads to people having a not too pleasurable experience in the main, and that's why people will shy away from it.
I don't know if you ever played Quake or Half Life Team Fortress back in the day, but those games were plagued by people with laggy, inconsistent connections who thought they were having a great lag-free game -- in reality they were shitting it up for everyone else. Games do a great job of interpolating trajectories and hiding packet drops... but you can't hide delayed kills or bullets flying through someone. It would get annoying fast.
I said before, I'm 3G gaming now and then when I'm out and about by tethering my 3DS to my phone. It works great sometimes, I got the MGS3D demo downloaded in no time at all, and I've played a fair few Mario Kart games... but its not without issue, and I don't blame developers for avoiding native 3g support in faster online games.