Nope, the wireless matrix was designed to make the grid more resilient from attacks in general. Think about it this way. With telephone lines today, you take out a wire, and you can cut off an entire building's communications. Take out a couple poles, and you can cut off an entire town. The Wired matrix was the same principle. With wireless, now as long as someone within signal range of your commlink has a connection to the matrix at large, you have a connection to the matrix at large, making it far harder for the entire grid to be taken offline, unless you're in dead zones (like parts of the Barrens, or out in the wild). Remember, the Wireless Matrix Initiative was being drawn up before Deus's existence was even known to the corporate types at large. They had a good five years or more working on the tech before implementation started going up just after Crash 2.0, where people saw how vulnerable the wired matrix was.
The reduction in power newer AIs have seems to be based on the fact that they're no longer 'born' in massive server farms that serves the main computing needs for the North American HQ of the megacorp best known for software, but can wake up in, say, a drone or your toaster.