It's hard to make a statement about average quality without a lot of data, but the total variance in quality is certainly increasing. Owners/companies that have strong engineering processes and standards are still building high quality projects and with the benefit of improved technology, it's much more reliable than circa 1970s stuff.

But there are also a lot of failures caused entirely by project management SNAFUs, poor communication between contractors on a project, inadequate testing, etc. that are completely avoidable and I personally as being largely caused by the diffusion of responsibility that occurs when a company is no longer capable of turning a wrench without hiring a contractor.