I'm still bit baffled that people are getting so hung up on welders in the trailer. Talk about not being able to see the forest for the trees...
It's not the welding per se, it's what the welding represents. That is welding represents a 20th and 21rst century level of technology while the movie is set in the 23rd century where things like welding would be antique at best. Welding shows a lack of imagination and a reliance on what's been done so many times before. The same goes for the "aztecking" or panelled look. It's old had and makes the ships look more like something our of the present and less like something out of the future.