Static IP Address

I’ve found multiple recommendations to set a static IP address for my devices and found several instructions for the steps. It appears that I’ve run into a brick wall though. Currently my router config shows the DNS servers are dynamically assigned by my ISP (Mediacom) and that this should be set to two fixed addresses which also go into my openelec config. This is approach is also covered by Netgear for my router.

But Mediacom has told me they can’t (or won’t) give out DNS address for residential accounts, and the only possible solution is to upgrade to a business account. It’s like I’m the only one in the world who wants to do this

So what happens if I don’t have static IP’s? Maintenance when I suddenly lose connections between clients and servers? Need to understand the pros / cons / values