^If you look over the whole history of ST, there's plenty of evidence that cloaking devices aren't a single technology, but a succession of different technologies that get penetrated and then replaced by new stealth systems in an ongoing arms race between concealment and detection. Consider: In "Balance of Terror," the Romulans' cloak rendered them invisible to optical detection, but their ships still registered on motion sensors; yet by "The Enterprise Incident," that problem had been solved and the ships were totally undetectable. By ST III, Klingon cloaks were detectable by a visual distortion, and had to be dropped before a ship could fire; yet by ST VI the Klingons invented a new type of cloak that had no visual distortion and that could be kept up while firing. And Spock figured out how to penetrate that type of cloak. Yet by TNG, over 70 years later, cloaking technology is impenetrable again and ships do still need to decloak in order to fire.
So canon already gave us several cycles of different cloaking technologies being rendered obsolete and supplanted by new ones long before ENT came along. Therefore, ENT's 22nd-century version of cloaking is not a mystery or a paradox at all; it fits in just fine with all the other forms of cloaking that have been developed, penetrated, and discarded.
You make some good points. Though, my understanding was that cloaking had to involve the bending of light around an object to make it invisible not the use of a hologram projecting an image which makes the object blend in with its surroundings. However, I suppose that's just an argument from semantics.
King Daniel wrote:
Remember, for the spirit of Spock's comments to work (he didn't refer to the Romulans but the technology of invisibility in general), you also have to ignore or work around the cloaking Xyrillians and Suliban from Enterprise too. Looking at Trek's "big picture", cloaks very much weren't theoretical but something proven to work in the 2150's. Therefore, it's easiest just to go with the retcon.
Well, the Suliban having cloaking technology is probably due to Future Guy giving it to them and as for the Xyrillians, a similar argument could be made to explain it as I did for the Romulans since they also had holgraphic tech. Also, I believe it was only said onscreen that the Xyrillians had stealth. Though ultimately, that was a mere technicality.