In terms of the "Epic" feel of a Raid, I think you're right. The Coil was far more epic than Alexander, and the stakes in the Coil were a lot higher. Part of the problem is the nature of the Primals we're dealing with and their worshipers.

Spoilers, for those of you who did not complete Bahamut's story line.

In the Coil, we eventually discovered that those responsible for summoning Bahamut were captured dragons that were left in a state of suspended animation and perpetually tortured for 5000 years, and the God they summoned was a EXTREMELY ANGRY MONSTER who wanted to destroy EVERYTHING. By comparison, Alexander is just... there. I don't take Goblin's seriously, for one. They have some interesting Tinker Toys, but there's not a single Goblin that has been even remotely intimidating, so it's difficult to take them seriously. Half the time I'm like, "meh, even if we lost. Who cares? They're Goblins. What's the worst they could do?" And Alexander himself doesn't seem to give a hoot. He's idle. He has no voice. He has no will. I know that's because he's gathering Aether to awaken, but right now he's just a cosmetic environment for us to fight in. By comparison, I don't find him nearly as intimidating as Bahamut.

That being said, it's still early. Bahamut started in a similar way. He wasn't complete, and in the first coil he did not speak or move, so there was a sense of tension that at any moment he might wake up. Alex is similar in this regard, and I'm willing to bet SE will play off of this with each new set of Alex raids, but right now he's just a lump in a lake. We don't even really know what he's capable of. Bahamut had a pretty impressive CG scene where he leveled the Cartenau Flats. Alex has a few rumours and some foggy history .... Not really impressive by comparison.