Psychologically, I don't like a par 5 where I have to lay up off the tee (due to running out of fairway, intervening water hazard, whatever) so lengthening it to where that wasn't necessarily might make it easier in some sense. Making a driveable par 4 or reachable par 5 longer so it must be played in regulation might make it easier, especially if one decides there's no point in hitting driver off the tee and plays a club less likely to find trouble.
But when you get down to it, given that you can always play a shorter tee shot from the "shorter tee" to where you'd play to from the "longer tee", it is hard to argue that shortening can ever truly make a hole easier. It is only made easier in our minds, or within the limits of one's biases as to how the hole should be played.