No, it really isn't. Talos worship doesn't stop, it just goes underground. Legate Rikke is a Talos worshipper, as you find out upon executing Ulfric. Heimskr is still allowed to preach in Whiterun. The 'ban' is just a temporary thing, and doesn't really have any teeth - the Empire doesn't enforce it, only the Thalmor. When the Empire regains its strength, Talos (and the Nine) worship will be restored. The Thalmor are beyond foolish for thinking it can be eliminated.
Also, interesting to note, the Thalmor (with the exception of the occasional Justicar ambush) mysteriously disappeared from Skyrim after the Civil War ended with the Empire victorious. The ones in Understone Keep are gone. There are none at the Thalmor Headquarters in Solitude. The Embassy is completely empty (no guards, the barracks are empty). I have yet to see a prisoner escort, and I've been looking. Not sure this is anyone else's experience, but it seems to me that they know they're [censored]ed and GTFO. And since they're the only ones that enforce the 'ban', Talos worshiping will return.
Also, the last 'pillar' holding Mundus in place is the Throat of the World. This is one reason why I will not side with the Blades to kill Parthunaax.
Also, to quote Legate Hrollod: "What the rebels like to forget, is that the Empire is what's keeping the Dominion out of Skyrim." The Empire are still enemies of the Dominion. Return them to power, and the evil Aldmeri Dominion will be destroyed.
Symbolism is rather important for mythical beings(To quote Sheogorath, symbols are everything). Being cut out of the pantheon is quite damaging to Talos, even if you're secretly worshipping him. Hell there's even imperial propaganda that was written to influence the belief that Talos isn't even a god. This IS damaging to Talos.
The fact of the matter is, the empire is currently under terrible leadership. There was no reason to surrender when they did. If they wanted a treaty they should have made an actual non-aggression treaty. The WGC is a conditional surrender of the Empire at a time when their enemy was unable to attack or even muster any forces.
Possibly with
things could change, but the current empire is in no shape or form able to fight the thalmor. They've been letting their spies roam freely through their lands. Subterfuge is the big reason the Thalmor were so successful in the war, and now they're allowing them to do it openly. Mede abandoned every other province when the IC was threatened. The only reason the empire still remains is because one general disobeyed Mede.
There's still Ada-Mantia, and possibilities of Green-Sap(Doubtful), and Walk-Brass(Apparently still attacking Summerset outside of time) still being active, there's also a good chance that the hist as a whole are a tower given their immense root system.
What the empire likes to forget is that they're the reason the dominion is IN skyrim.