Both points are good ones but relate to the buy side. But you can't get funds back after the sale of shares for 3 days - and that's just to your trading account. I'd prefer one day settlement to allow for overnight transfers. This would allow more flexibility and you could withdraw funds in a couple of days instead of having to wait four or five days after selling shares.
I believe the T+3 was created for times before electronic transfer and trading when we had to cater for snail mail, and should be changed to T+1.
But it sounds as if everyone (except me) is happy with the way things are.
