When Titanic was built, she was the largest vessel afloat. She was a big step forward in many dimensions and internal facilities. The A380 is not.
Consider the heavy freighters of Antonov and that the 747 introduced double decks 30 years ago and, if I recall, there had been double decks before in prop-liner days?
Also - regulation. Since Titanic, countless rules were changed, even though she exceeded some of the design criteria and regulations of the day. Her sister, Olympic sailed until 1935, so there was not a general failure of the design.
If sonar had been invented 30 years earlier? Even if radar had been invented 30 years earlier, they could at least have 'seen' the above water part of the berg early enough to turn. The A380 will benefit, as all other commercial a/c do, from radar, ATC and TCAS at the end of the line.
The only reason that I shall be wary of using the A380 is becuase I know that BAA plc (who own and run LHR) will not have the infrastructure in place. They (and the carriers, I suspect) will not have the air-bridges properly manned and will still be loading and off loading people in dribs and drabs. If you need example, have you seen a 744 loaded through a single bridge and one-person-at-a-time?