The problem that many have with the Technology of Enterprise, is that Roddenberry (through no fault of his own) failed to realize just how fast computers and technology would evolve. Star Trek seemed so far out there during the sixties, but in many cases, what we have now surpasses, or comes pretty darn close to what was shown in Star Trek. Berman and Braga (correctly or incorrectly, that is a debate that I am not attempting to settle here) decided to try to make it so that Enterprise looked more like something that we would be able to build in one hundred years time than what Star Trek would look like one hundred years before Kirk. Unfortunately some of the stuff is probably more advanced than what was on Star Trek. What should happen eventually, is that the Phase Cannons are eventually replaced by Lasers because its determined that Lasers do a better job at penetrating Sheilding, and the Phase Cannons are renamed to what they are supposed to be...Phased Particle Cannons. Which because Particle Cannons do more damage to exposed hull, are merged with Lasers years down the road, maybe the last episode of Enterprise, to become Phasers.
If you go by the Star Trek Chronology (see my earlier post about that in the Warbird thread), which was written in 1979-1980, Enterprise actually got the date of the introduction of Photon Torpedoes down to within a decade. The First Federation Starship equipped with Photons, according to the book, is the Horizon class Starships. which was the first Federation Starship built under the United Federation of Planets charter. But several of the Earth Starship classes that were constructed before the Horizon, were refitted with Photon Torpedoes following its development.
The decision made by B&B is the problem of not only doing a Prequel (sometimes Prequels arent all that bad) but doing a Prequel thirty years after the original aired.