Mate I agree entirely it should be in HD but in all seriousness it makes little difference watching a footy game, movies and sci-fi stuff it does but sport in HD or SD unless you are a HD buff it should have very little impact on how you enjoy the game.
I have foxtel and also top of the range TV's and I have switched from 7 to foxtel when same game is on and I can't notice any difference, not that I am looking for one however.
If you're watching a game that's on both FTA (so 7/7mate) and Fox Sports, then it'll be a simulcast of the SD feed from 7 "upscaled" (poor hd imitation). So there won't be too much difference.
Compare a stand alone Fox game against a 7 game, and they're miles apart.