I used to bet, and i used to duel. None of these require direct transfers.
An option of ingame-transfer will result in some -underground- duels with no duel mode, and therefore more new scams.
Duelmode does its job very well and there is never a need to transfer TC quickly while dueling. The only situation is when your opponent pinged and you decide that you do not deserve a win, and wish to send his tc back. But this is not a thing that should be done really ASAP, he could wait for you to open your browser in a couple of minutes or hours.
Betting is done so you dont need ingame transfers, too. There is a command for any betting operation. The only things i have met that would need me to send tc - when OP is selling nudges for 500TC sent to him, an alternative to pay 1k to DP. So, to quickly buy a nudge you could need that. And the other one is when someone is doing market shit in the chat and wants to sell something. Both these situations can be considered as marketing and these have pretty much nothing similar with betting.
I do not think that this will save you from glitches/bad Internet connection. The game will need to connect with forums and do the operations through it, which could overload both the game and the Internet connection.