DBCC Usage on production system
First, find the person who put that job in place and have him/her tied to a chair listening to cats scratching a chalk board while you go for lunch. 

When done with that, compare your resource utilization and performance data for extended periods before and after the job runs. I suspect you'll see perf dips and a number of resources getting really busy after the job executes. You can temporarily suspend the job and monitor closely for a week to see what happens. I doubt you'll run into problems but as with all changes to a prod system, still keep a close eye for a while and make sure you capture perf, resource usage and waits data.

These sprocs are typically run in a test environment, especially for performance testing, to see how specific queries or the overall workload behaves on a cold-start equivalent. It can also be used to see how specific parts of the system handles unexpected load spikes especially storage. 

We have encountered a single support engineer whose standard perf tuning method involves doing these things on a production system; we couldn't get rid of him fast enough. Running all of them on a production system regularly is pretty close to rebooting your server daily to keep it healthy and doing it in the middle of a busy day for best results - really, really shouldn't.