Why the Archon 'failed' as an enemy.

Well done cliche villains are the best type of villains.

I agree. Loghain is an honorable hero who grew tired of seeing King Maric's son trying to put history aside for personal glory. He is also a father who saw his daughter being replaced by an Orlesian queen. The writing behind Loghain was great as well as the voice actor. His second, voiced by Tim Curry, was exceptional. Colfoley still nailed it with his thread. The Archon needed more and Colfoley explained it well. A perfect example of constructive criticism.

Would DIO count in this case?
WRYYYYYYYYYYY

Agreed on what you said.
This is how you do a villain IMHO. (Yes I am a Berserk fanboy)

I'm not quite sure how you managed to miss all of this - maybe because you don't care for DAO in general, but...

Loghain was the Hero of River Dane, the battle that turned the tide in helping Ferelden to finally oust the Orlesians from their 78 year long occupation of the country. Previously a commoner, his support of King Maric in freeing Ferelden from Orlesian rule is what motivated Maric to appoint him the Teryn of Gwaren and what brought him into the role of General of the King's armies. Loghain's dislike/distrust of everything Orlesian is not without reason.

He also carried some misgivings toward the Wardens, largely due to Sophia Dryden's rebellion. Following the events at Soldier's Peak, the Grey Wardens were banned from Ferelden for the next 200 years, until King Maric allowed their presence once again. Loghain did not understand that only a Warden could slay the archdemon, did not believe that it was truly a blight, and felt that Cailan's romanticized notions about riding in with the Wardens to defeat the blight were foolhardy.  He did propose an alternate plan at Ostagar, which Cailan rejected.

The bottom line is that Loghain took it upon himself to protect Ferelden - from Orlesian influence, from the darkspawn, from an impetuous young King whose judgement he questioned. He genuinely believed that he was doing the right thing, making the hard decisions, doing what had to be done, etc.

Whether he knew of Arl Howe's intention to overthrow the Couslands before the fact is... subject to debate.

In any case, Loghain was every bit as complex of a villain as any other I've ever seen in any of the other titles - including Meredith, the Arishok, Saren, TIM, etc.