Arduino's are usually $30, though you can get the clones for $20. The ethernet shield alone is $45. The cheapest Arduino-a-like with built-in ethernet, as far as I've found, is the Nanode v5, at $40 in unassembled kit form.
Many of your other points are valid. For tons of projects a Pi would be overly complicated overkill, but I can think of many times when I'd want more video in/out capabilities, plus the ability to blink some lights, drive some motors, and accept non-usb sensory input.
http://wickeddevice.com/index.php?main_page=product_info&...
Many of your other points are valid. For tons of projects a Pi would be overly complicated overkill, but I can think of many times when I'd want more video in/out capabilities, plus the ability to blink some lights, drive some motors, and accept non-usb sensory input.