You forget how the Clone Wars took multiple seasons to improve graphically, in design and animation. Compare season 1 of the Clone Wars to an episode from the later seasons and it’s a vast improvement.
Similarly, Rebels is having to do the same. Their budget per episode is a fraction of what it was for Clone Wars and yet it’s improving far more quickly than the Clone Wars did.
I had my own quibbles with Sabine’s design but there’s really no denying that the show can be beautiful:
Animation and art design aside, what’s really important is story. Rebels hasn’t suffered the same pitfalls that Clone Wars did overkiddifying everything early on. They had a clear vision from the start of where they want to take the series and its been moving forward at a great pace. The second half of season two is promising to be quite the ride.