"No Ethernet" is not a serious complaint
Alistair - I think that you have completely missed the boat with the "No Ethernet" complaint. There are three base models in the 3015d series, and you manage to review the ONLY ONE that doesn't have an Ethernet port.
Not every business situation warrants having an Ethernet port in the printer, and I have deployed quite a few workgroup printers in the past couple of years that attached to the network wirelessly (and in HP's case, wirelessly means attaching a EW2400 via the USB port that you also questioned)
While I do admit that the price is a bit on the high side, if the application is on-demand printing of prepared forms and documents it can be less expensive in both dollars and floor space to deploy one of these than a less expensive printer AND a companion computer to hold the forms. It's not a large market - but it is a market that that is addressed with this printer.
@Chris Cartledge on Electricity Consumption
You might want to consider that a company does not spend this much money on a printer with a maximum duty cycle of 100,000 pages per month for it to sit in power save mode all day. Typically, the printer will either be actively printing or in standby waiting for the next print job - and it is going to be less than 30 minutes before the next print job. Given that the average business that uses this type of printer is open more than 15 hours a day, your assumption that the printer will spend the majority of time in sleep mode might need some reconsideration.