Kernel modules not only for hardware support but provide features too. God example is handling AX.25 amateur radio packet protocol or Layer3 ROSE or NETWORK protocols on top of AX.25 These are implemented as kernel moduls. Are you saying to drop support for them or tio build into the default kernel? Just another example is Ethernet bridging.
While Model-B has only one Ethernet port you can add more using USB/Ethernet adapters and so on. BTW, USB. There are many different type of hw extensions with USB, sound cards, WiFi, etc. may need kernel modules.