It's actually a fairly common method of installation, even if it does seem a little hokey - likely all in the name of cost savings.

Any of the OEM style mounts (meaning if you buy them from the dealer, or Moog, etc.) are all going to be very similar to stock - might be able to find some stiffer bushings, but none of them are going to bolt to the tower. In order to bolt it to the tower, you'd have to totally re-engineer the top of the strut assembly to include a bearing so it could rotate when you steer - and given the shape of the housing at the area where the bushing sits, it would probably be a pretty extensive modification; not sure it would be worth the trouble and expense on what is essentially an "econobox" car...

The Aveo isn't really designed to be a bad-ass rally car, more a basic transportation device with a low cost...