Then you obviously haven't listened to them nearly enough.
Honestly, A7X is kind of hard to defend, but I'll bite. They remind me of Iron Maiden in a lot of ways. Yes, Iron Maiden has Bruce Dickinson and Steve Harris, but the guitar players in A7X have a very good sense of melody (incorporating the neoclassical elements in songs like Bat Country). Their harmonies often remind me of Maiden's finer moments.
As far as Mastodon goes, they remind me a lot of Priest. They started out doing the sludgy thing, but they progressively got more accessible and popular. They started to break into a more progressive metal direction with Crack the Skye, much in the way Priest broke into the NWOBHM scene with albums like British Steel and Screaming For Vengeance.
Either way, this argument is kind of pointless, since I've seen you hating on WAY more than the 3 bands you listed. But whatever, it's quite obvious that your stubborn love for the classics hurts your judgment of newer music just because it dared to stray from the safe haven of gallops and mid-tempo rockers.