It can cause some issues down the road if you completely disable DHCP and try to run everything as static IP. Mainly, the issues I've seen if you have to know exactly which IP addresses are in use and where. Otherwise, if you go to add a device onto the network you have to know what IP address you can use that isn't already taken.
Another way you can set up an assigned IP address is IP address reservations, which was mentioned earlier. This can be done with nearly any router today, you just have to go into your LAN network settings and there should be an option to add a reserved IP address. This will require looking up the MAC address of the desired NIC though.