I had heard that the reason that Clark wouldn't ever wear the suit on the show was because they had never got the green light to do so from the powers that be.Now I don't know how true this is and furthermore,I don't know who exactly they would have to get permission from considering that WB owns the rights to Superman and all of DC Comics.Either way,I kinda understand where he is coming from,but doing two Cheaper By The Dozen movies,I'm sure,isn't necessarily a career builder.
I've been watching Smallville since the very first episode and I think that I've only missed one,maybe two episodes during it's entire run.I really thought it was pretty good in the beginning,even though I don't consider myself a huge Superman fan,but the show has really gotten long in the tooth over the past few seasons.
I wouldn't mind if he never wore the tights on the show,but I think that it would be kinda cool if the last shot of the series was Clark standing in front of the suit,looking at it and about to put it on for the first time.
That was one of the reasons but Tom Welling also had it written into his contract that he doesn't wear the suit. I've been watching Smallville since the beginning as well (and I'll continue watching the show because I've invested this much time into it and I want to see how it ends) and I think the show started to go down hill around Season four. That's the season where he flew in the first episode (and that episode only) and Lana all of sudden had witch powers.