Most manufacturers will only recommend removal by a licensed plumber for warranty purposes. They can, however be removed and replaced with plastic lined galvanized nipples that are available at some big box stores and plumbing supply retailers. Some plumbers will even use brass nipples. I think there may be some confusion about the melting you mentioned. Melting of the plastic insert of the nipple, and potentially the dip tube of the tank, typically comes from soldering the copper fittings after connecting them to the nipples. It's always recommended to pre-solder the copper female/male adapter on to a piece of pipe approx. 16" long and allowing it to cool before threading it on to the supply nipples on the tank.
Regardless of the type of nipple used, remember to get some dielectric unions to reduce corrosion to the nipple-to-tank connection.
I prefer piping the heat trap instead of relying on the nipples as even manufacturers will admit to the noise they cause. If possible, I pipe 12" vertical up, 12" horizontal then 12" vertical down. Adding insulation is a bonus.