The even feed puts traction on the top layer to make it move at the same rate as the bottom layer. If there isn't enough pressure on the presser bar, it won't do much good - it will just make sure that you are applying those teeny tiny stitches evenly to all layers. ;)
I only have a couple of computerized machines, so I'm not up on all the latest technology - but I think there are a lot of things that human judgement can do a lot better than a computer can. If you can override that automatic sensor's input and increase the pressure, your stitches are probably going to lengthen nicely. :)