Yeah, I know about that. I hope, they evolve, though. I think Swampert is so boring. Quagsire has so interesting abilities but subpar stats. Whishcash has a very interesting moves and a nice ability, but again, lacks the stats. Same goes for Gastrodon. I'd be so happy about a Quagsire or Whishcash evo. =)
Also: Yeah, Grass/Ground has awesome potential, but it needs to be fast. Thus, Torterra sucks, sadly...
Torterra has amazing sweeping ability with Rock Polish set, perhaps its most feared set in UU. It's not the fact that it's a bad pokemon, but it doesn't have the best stats to use them. Grass/Ground is also not the best typing, being 4x weak to ice, as well as bug, poison, fire, and fire. If there were to be a new Grass/Ground pokemon, it could make OU easily if it had around 80-90 base speed, access to Rock Polish, and a decent enough attack stat. So no, Torterra doesn't suck, it just doesn't have the right stats in the right places to be as effective as it could be.