Pretty obvious from this thread why full service hotels charge for internet access - because most people can stick their client or employer with the charge.
Alas, I travel about 25 nights a year on my own dime, so this doesn't work too well for me particularly when I book via priceline. However one plus to the Marriott policy is that it disincentivizes me from lugging my laptop on short leisure trips as I am better off simply checking email from my phone or an internet cafe. Also means less time spent in the room and more time spent on the beach.
When I do have a choice, however, I will definitely favor Hyatts, Hiltons and possibly Courtyards or RI which offer free terminals or even better free in-room wireless.