I may be just plain simple, but how do you allow resurfacing of a lane and travel on it at the same time? If shifting the traffic is part of the problem you'd better hope there is never a wreck that blocks a lane and traffic has to detour around it.
I think they have already found certain welding techniques that are no longer allowed. It goes back to what I said about flexibility. Most structures cannot nor would you want them to be completely rigid. First, they cost would skyrocket from over building. Second, they would require even more maintenance and inspections. Next time you fly a wide-body, take a look at the wingtips; if there is any turbulence, you will see it flex up and down. Were it not to do that, the cabin would have to be made smaller because more of the aircraft weight would be in the structure. And the ride would be considerably rougher.
The ultimate cause(s) will probably be minor but linked to others until the final straw breaks. And
Sandbox is correct, it will take time. And the movement you felt has been happening since before that bridge was even opened. You are simply more aware of it now, for a while, anyway. I don't think we can really continue living as most of us want to and completely avoid bridges, airliners, domed stadia, etc.
Let's just hope that the agencies that are in charge of maintenance can keep the money handlers attention to get better inspections, quicker repairs and better designs.