Please turn it up to 11

I doubt that I am exceptional in this: I have found that with my current character levels even level 10 PvE has become dull, lacking challenge.  I'd like to have a level 11 where I lose sometimes.   

You might be concerned that a higher level would presumably deliver rewards faster, which might lead to our outrunning the arrival of new characters and maxing out all of our characters, at which point we'd leave the game---but I think that if we can't find a more challenging PvE many of us are likely to leave the game anyway.