Wild card virtual servers ?

Wildcard VS are useful when the destination is unknown (any). I will give you two examples, but they are virtually unlimited depending on your use case.

What if you have servers in your infrastructure that needs to connect to the Internet to download binaries using HTTP and your BIG-IP is their gateway ? Also, you need to load balance through 2 ISP with your BIG-IP when going to the Internet. To allow the traffic through, you could use a Wildcard VS 0.0.0.0:80, disable Address Translation and load balance through a pool of gateways (ISP).

Another example could be, you are loadbalancing forward proxy caching device and you want to ensure that for the same destination, you use the same caching proxy (a pool member in this case) (so a.com requests are only cached on cache1 and not others to avoid cache duplicates). Clients requests various websites a.com, b.com etc... that resolves to various IP addresses 1.1.1.1, 2.2.2.2 ; to allow that traffic through you will need a 0.0.0.0:* VS in place and you may use a destination address persistence profile to achieve the requirement. Connection to 1.1.1.1 is allowed and loadbalanced to cache 1; you set a persistence record. Future requests to 1.1.1.1 will persist to cache 1.

In the end, it's just an 'any' destination that needs processing in your BIG-IP.