D-Link products tested for the Recovery Mode that do not support this mode: DGL-4500 and presume all DGL Series routers.
Any other products found to support or not support this option, send me a PM and I'll add it to the list.
There are many reasons you may want to consider updating your router’s firmware, here are several of them.
One good reason why your router manufacturer may put out a firmware update is because they are trying to fix a vulnerability that was detected in the current firmware, updated firmware is similar to system updates (as in Microsoft’s Windows Update).
The attacker could pretty easily block user access to the router as well by changing the admin panel access password so that any malicious changes would be pretty difficult to undo.