Thunder Wave's 100 Accuracy is offset by the Ground type's immunity to it. I think it's balanced.
It's also offset by the fact that Paralysis is the most useless of the status moves.
Frozen? Can't do anything at all. Sleep? Can't do anything unless you have special moves. Burn? Massive attack drop and you take damage every turn. Poison? Damage every turn, increasing damage if you get toxic-style poison. Paralysis? Go slower (which only matters for some Pokemon) and have a very small chance of not doing anything for one turn.
As someone else pointed out, Spore is far more broken. 100% accuracy on the 2nd most harmful status in the game? Yeah why not just make a 100% accuracy freeze inducing move to go with it?!
"Jak and Daxter does not have a sequel so that doesn't prove anything." - DesperateMonkey