What is to be lamented is not that Owen did not recognise C-3PO but that we are asked to accept that Anakin built him in the first place. I feel that this was a lazy introduction for such an iconic character.
I feel it would be much more interesting to have C-3PO and R2-D2 together from the start and have the suggestion that they are, in fact, much older than any of the principle characters (with the notable exceptions of Yoda and The All-Powerful Sarlacc), as, indeed, machines can be. Keeping them as our guides through the saga would work much better, don't you think?