Resigning so soon is a logical thing to do but, tactically, I was thinking it might be better to stay in place during the election post-mortem period then, when all the wrongness has been wrung out and a new direction for the party has been chosen, that would be a more logical time for protagonists to launch their leadership bids. No point having a second union-installed puppet at the helm.
They need the general public to become well acquanted enough with the new
leader for them to appear electable. In Ed's case, four years' exposure was, as observed above, long enough for the feet of clay to become apparent.
It would be ironic if there was nothing wrong with Ed's image but the party's collective failure to sense the public mood and promise-match on the EU referendum, they could have retained some of the votes they unwittingly swept into UKIP's lap.
Or was it his passing resemblance to the avatar of Twitter character called "SixthFormPoet"?