I agree that kernel-space drivers are a relic of the 20th century.
You can write fast network card drivers in userspace too. You map the physical DMA memory into userspace and cut out the kernel entirely. Interrupts don't even come into the picture when you're polling several packets per microsecond. Lots of those cards nowadays come with high-end packet I/O libraries that are implemented in userspace. Myricom Sniffer10G, Intel Data Plane Development Kit, ntop.org DNA, etc.
You can write fast network card drivers in userspace too. You map the physical DMA memory into userspace and cut out the kernel entirely. Interrupts don't even come into the picture when you're polling several packets per microsecond. Lots of those cards nowadays come with high-end packet I/O libraries that are implemented in userspace. Myricom Sniffer10G, Intel Data Plane Development Kit, ntop.org DNA, etc.