Really? On my 2GiB system in a typical usage I have 1.1GiB physical and 1.9GiB virtual RAM free. Setting the update period to 10min and assuming each update uses 1s of CPU time (a gross exaggeration, I suspect) it would still use less than 0.17% of CPU time. If that is a burden, you need a faster system anyway! BTW, Outlook Express is set to download all new mail and news messages every 5min - a much higher system burden.
Not just one click away. I work on the keyboard for 99% of my work (as I suspect is the case for most of those not dealing with games or art) , taking my hand off the keyboard to make a click is a nuisance. Furthermore, I like my mail to be home delivered, instead of going to the post office to check whether or not something new arrived. To me, browsing for news is like taking a trip more often wasted than useful.
How about someone answering what negative effect would arise from being able to set the "what's new" display as my default, so after I use "Mark forums read" I would automatically see the "nothing new" display, instead of the full list of available fora?