It's been years since I stayed at the hotel, but the website says that the rooms were remodeled last year.
As you can see there are windows, they just face the interior courtyard rather than the airport parking lot.
Which is also why the exterior corridors, giving the Motel 6 look. When I stayed some years ago I found the service good.
The hotel is operated by Marriott's Host division. The ugly brown color is the result of the hotel being built to match the design of SMF's original terminal complex, now known as Terminal B. I would imagine that with the opening of Terminal A some exterior update will be done in the near future.
A little history. The hotel at SMF was built to open at the same time that passenger service was moved from what is now Sacramento Executive Airport to the then completely new SMF. One concern when the airport was built in the 70's (1972 I believe) was that it was "way out of town" and there were no hotels in the area (the same problem facing many all new airports such as DEN). So SMF made sure there was an onsite hotel. With several conference rooms, the hotel also over the years has proven convenient for travellers to fly in from around California to hold 1 day meetings in the state's capital city.