Security risk of opening port 111 (rpcbind)?

As far as I understood rpcbind is used for listing active services, and telling the requesting client where to send the RPC request. If a host listens on port 111, one can use rpcinfo to get program numbers and ports and services running; For example look at below:

root@bt:~# rpcinfo -p x.x.x.x

program vers proto port

100001    2   udp    111  portmapper
100000    3   udp    111  portmapper        
100005    3   udp   1048  mountd
100022    1   tcp   1047  nlockmgr    
100021    4   udp   1047  nlockmgr
100026    1   tcp   1039  status
100029    1   udp   1039  status
100003    2   tcp   2049  nfs
100003    3   tcp   2049  nfs

What is the security risk of it?

Where we usually need to open port 111 and when can we close it without any other services fail?