For people who live in that catchment area, it's as important as the rest of the journey. I don't know where you live or how often you use the Central Line north of Stratford but at peak times the trains are crush loaded between Leytonstone and Stratford. They come in three minute intervals, they're eight coaches long and it's difficult to get on! They're also pretty full off peak. As many passengers will be going to the points I mentioned previously, it would/will be sensible and constructive to extend the Victoria Line the two miles (as the crow flies) to Leytonstone.
I don’t know how often you use the Victoria line, but at Highbury and Islington each morning it is not unusual to let 4 or 5 trains go before you can get on. This is on a service with a train every 100 seconds. Stick a load of people on it from Leytonstone, and that problem goes back to Finsbury Park and Seven Sisters. In which case you’ve just spent a billion quid to move a problem from one part of NE London to another.