I wish Dorion had more constraints on him. When he's been given the greenlight to spend money on new acquisitions it's largely been a disaster.
There's no question that, in general, players don't want to play in Ottawa. There's the occasional case of a local guy like Giroux and we've had some luck attracting Russians (Gonchar, Kovalev, Dadonov, Tarasenko), but I've never been one to blame Dorion for failing to acquire a guy who has a NTC. I'm usually the guy in the trade proposal thread pointing out that a player has a NTC and isn't a realistic target.
Dorion doesn't understand how to manage risk. Trading as much as he did for Duchene and DeBrincat, who both were two years away from UFA status, is not good risk management considering my point above - players generally prefer to play elsewhere. Dorion should have been focused on adding players with existing term on their contracts that don't have the option of leaving. It can be difficult to do but that's the reality we deal with as a small market Canadian team and I don't think striking out by swing for the fences shortsightedly is something he should be praised for.
I have stated for a long time that GMs get way too much credit or blame for draft picks. GMs typically don't overrule their scouts and most of them have enough on their plate. They aren't the ones traveling throughout NA to scout draft eligibles. They may have some input in the 1st round, but beyond that it's unlikely they play much of a role on draft day. Dorion himself has said Mann runs the draft, so credit for Stutzle, Sanderson, Tkachuk, etc... or blame for Boucher, Thomson, JBD, etc... falls on him primarily.
As has been pointed out, it also shouldn't shock anyone that the team has a bright future. When you blow up a team, trade numerous star players (Karlsson, Stone, Duchene), several other good players (Brassard, Pageau, Hoffman, Dzingel), and then suck for half a decade, it's very difficult to screw up so badly that your team doesn't have a bright future. That's the reality of spending so much time at the bottom of the league selecting high in the draft, as well as racking up a large number of prospects and quality picks from selling existing talent. Sens had more talent to trade away than any other rebuilding team in the last decade. We really should be in a better position than we are right now given that, and Dorion's failings are a big reason for that.