Games should not be designed around the experience of a player who is lagging. If I am lagging then a short TTK is worse for me because I can get hit and killed even before I realise...it works both ways you see. In fact that's worse cause with low TTK the lagging player will always lose and this is where games start to incorporate ridiculous amount of lag compensation..and it all turns to shit for everyone. Also please don't exaggerate by saying things like half an hour to kill, an encounter barely lasts more than 5 seconds.
I've played Halo from third world countries where the lag is high and I've played it from my resident country UK with little to no lag and I've managed fine because high TTK provides me with a fighting chance rather than turning the match into who saw who first.
Also Team Fortress 2 on PC has the highest traffic out of any FPS on PC and it has high TTK to very high TTK.