A little set back like a lost lander should not discourage visionaries.

At the beginning, some people thought we were a 'me too' mission: Send a lander to Mars and take a picture.

It would be nice to know where Luna 9 is, the first successful lander. We may want to set up a register of historic sites, not to be disturbed by future missions or hardware impacts. To do that we need accurate locations.

All the ingredients for life on Mars exist.

You'd also want to use lunar rocks as building supplies - it is so costly to lift even an extra kilo of steel into space, running to many hundreds of thousands of dollars,

Unlike (the NASA) robots, Beagle 2 won't be going sightseeing. It is intent on discovering where there is or was life on Mars. It is happy to trade measurements for mobility.