He was in a lot of terrible movies, so I don't think he necessarily had the highest standards. The remake of Rear Window is one of the worst things he ever did, so I have to assume he might've gone back to a good Superman script. That said, Michael Keaton was the one I NEVER thought would return, and here it is. He was too worried about being typecast and got a bit too big for his britches in the 90s, then had a huge comedown/humbling, and I think he's back (even when he doesn't need to career-wise) because he realizes for better or worse Batman will be his defining role he's remembered for. That was even more the case for Reeve, and if they could've made the situation work he would've done it. Let's be fair, Smallville's Rosetta is not exactly high art.