Metal bridging serves the same purpose as wooden bridging. All it does is prevent a joist from trying to roll over (deflect) in case it should be overloaded. Why would you want to replace bridging? The top of the bridging is nailed into place before the subfloor is installed. Trying to nail it in afterwards would be difficult, if not impossible. Solid blocking would be easier to install after the fact than bridging. If the wooden bridging was installed sloppily and is hanging below the bottom of the joists, then I would pull the nails and saw it a little shorter and renail it without loosening the top. Installing drywall against the subfloor is not going to gain you much in soundproofing. Installing a ceiling will do far more.