I wonder if you could use an air "force field" to capture the rocket. e.g. a circular arrangement of air turbines, dynamically adjusted to smoothly capture and land the rocket. Has something like this been tried?
Edit: Every thread on HN or reddit usually has people suggesting other methods of landing rockets that require huge, specialized infrastructure. The primary goal here is to land on Mars without large or complex infrastructure. So even if you think you can devise a cheaper or 'better' system, if it doesn't work on Mars, it doesn't work at all.
That said, there is complexity in having higher performance valves and such to get a fast system response, but still that's improved performance of existing equipment as opposed to adding more stuff.