I've been really impressed by Hoolahan and the step up he's made to premiership level but not bringing him to the Euro's or playing him in the qualifiers is hardly an injustice. It's Trap's system that creates our competitive advantage against teams that may be able to call on a higher calibre of player. Were Trap to pick the form 11 for the Euro's and play Hoolahan off Robbie up front, or in the middle of the park beside James McCarthy or Gibson then he'd be up against players like Iniesta, Pirlo and Xavi. Realistically, Hoolahan isn't at the same level as these players. Sticking to our current, tried and tested set-up and using our core rigidities are Trap's methods, and qualification to the Euro's stands to justify those methods.
I wouldn't be critical of Trap leaving someone like Hoolahan out. The only alterations I'd like to see wouldn't be from a tactical perspective, but from a personnel perspective. I think Trap could keep the same shape but ensure that McClean is in the squad, and maybe consider Gibson or McCarthy in the middle of the park. Maybe also have a look at Walters up front, and perhaps Dunne and O'Shea at centre-half.