That's how I feel about Connor too.
Which is why they made DA2 the way it was. I remember Gaider saying that stuff was a mistake... the "middle" path in DAO that won all the time. Gamers are always going to choose it if they know it... that's what games are about: winning and optimizing. But these should be a little different than other games.
I don't think the thing where you can save both Amaranthine and the Keep was a mistake, though. They made it credible, and you do have to work for it. If anything their mistake was that you can't do anything to make Amaranthine more secure, since most Wardens probably know of the tunnels and the Wardens who decide to use the smugglers instead of destroying them see evidence that the tunnels endanger the city. You then have no option to do anything about it.
By the same token I don't think Bioware did well with the thing where you can't save Leandra Hawke. Her killer continues using a facility that Hawke and Aveline know him to have used (assuming First Sacrifice was completed,) and we see no signs that he had to dodge or wait out a stakeout on that hideout even if Aveline is already the Guard-Captain. Yeah, they're spread thin and couldn't spare too many people for this investigation, but "the criminal returning to the scene" is something worth posting someone to wait for. They don't even need enough people to stop him, merely enough to tail him. Note that this isn't a complaint that Leandra automatically dies: that could have been done well if, for example, Quentin had waited out or slipped past the stakeout or just not used the Dark Foundry after he'd been tailed there. Or they could have not let you make Aveline Guard-Captain until long enough after First Sacrifice that she could credibly judge the killer must have been back and left due to not knowing that the killer was using that as his base (though doing that well would require them to hide the "Hidden Trapdoor" into the killer's lair better to make it clear that that's not due to every member of Hawke's party in First Sacrifice being blind.) While they're at it they don't really give much reason why Hawke doesn't try to use Gascard's abilities to find Quentin before the emergency happens; they could have explained it by saying that Quentin was warding his lair, and that Quentin either lost his concentration on the wards or chose/had to drop the wards when he activated his homunculus, but they don't bother.
Tl;dr: I don't care whether they let us use an optimal route, but if they don't let us use one I'd rather they put us in a situation where there isn't an obvious optimal route that we're only barred from by game mechanics.