Because domestic OD performances in ENG does not generally equate to ODI success. So you shouldn't look at is as "Oh Trott has done well opening for Warwickshire, he must be a good option to open in ODI cricket". Trott has only opened as i said this season, Denly has being doing so all career. So for now Denly definately should be given more a chance to see whats up.
Plus now that i'm checking the
list A records this year. Denly did slightly better than Trott.
I'm not. Denly though domestically has shown domestically along with his solid technique he can be innovative in his shot selection. He has shown glimpses of that in the few ODIs he has played so far.