You forgot to mention Khyber, that one's quite important in Eberron, but overall, as much as it pains me to say it, I agree. Most of Eberron's planes are pretty uninteresting subversions/reflavors of planes from the Great Wheel and Manifest Zones are super under-used in Eberron. The main thing that makes Eberron's planes of existence better than those of the Great Wheel is that they aren't attached to alignment and mostly aren't redundant. And, of course, Dal Quor is probably the best addition to cosmology that Eberron introduced.I say this as an Eberron fan: the Eberron planes are meh. A few planes are important as invasion points (Dal Quor, Xoriat) but the rest are just variants on the regular Great Wheel planes (fire plane, fey plane, shadow plane, chaos plane, etc). Permanent Manifest zones are handwavium (explaining why Sharn is the only city built vertical) and the whole waxing and waning influence either happened at the speed of plot or were as annoying to track as Krynn's moons. I've run two long-term Eberron games, and I think planar influence (heck, Eberron's planes themselves) have never come up, Dal Quor/Inspired notwithstanding.
People gush about Eberron's planes, but I don't think they're within the top ten best things about the setting, and if WotC said they were just Eberronian names for the planes of the Great Wheel, I wouldn't care less.
However, once I buy Exploring Eberron, my opinion might change a bit. I heard that its approach to the planes is much better than their usual depiction, just because it gets to go more in-depth than the other Eberron books.