Why Need To Change Default Router Login And Password

My wireless network: 1 Computer with ADSL modem and wireless router; The modem is connected in WAN port of router; and the computer is connected in LAN port of router. 1 Notebook with wi-fi receptor. Why a need to change my default login and password in wireless router If:

1 - The connection is encrypted with WPA2-PSK and AES with a very strong password (25 characters including letters, numbers and symbols);
2 - The SSID broadcast is disabled;
3 - The router have a MAC filter for only the my home computers;
4 - I allocated the number exactly of IP numbers to my home computers;
5 - The router Firewall is enabled and all computer of my home network have a good Internet Security (Firewall + Antivirus + Antispyware + Antispam + Antiphishing etc).

Is strictly necessary the change of my router default login and password?