As with anything involving the government and Amtrak, there is no way to be sure just exactly way the Pioneer and the Desert Wind were discontinued. They both were short trains--four to five cars each and one locomotive (F40)--but were usually well patronized. Mostly it was chalked up to not enough passengers and not enough money to keep them going. I wonder if Union Pacific was in on it, didn't want the service over its lines. There was talk of using the Pioneer as sort of an express train--in addition to carrying passengers, it would also carry perishables and other time-sensitive packages, but UP balked, thinking it was too much competition for its freight lines.
It was indeed a site to see the three trains connected together. With the Pioneer and Desert Wind were fully Superliner equipped (about 1982), the train traveled as one to Salt Lake City. The train could be up to 16 to 18 cars long. Sometimes there would be an extra diner put on. It was great watching the train snake around curves, especially through the canyons. At Salt Lake, the train would be split apart into three sections. The CZ to Oakland, the Desert Wind to LA, and the Pioneer to Portland and Seattle. I was there to watch them do it once.
From the late 80s (I think), the Pioneer was separated at Denver, so it could travel through Wyoming to the Northwest. It restored rail service to a route that lost it in 1982 when the San Francisco Zephyr became the California Zephyr and assumed its present route. The train did serve a number of communities that had no air services and where the train was a viable option for intercity and interstate travel. It's a big state, with major towns sometimes a hundred miles from each other. Winter conditions made driving trecherous even on the Interstate. So, there was a need for the train. Probably the most scenic part of the trip in Wyoming is the section through Echo Canyon.
My favorite parts of the trip were: Durke Loop, the descent (or climb, depending on direction of travel) between Baker City and La Grande, the ride over the Blue Mountains (between La Grande and Pendleton), and especially the ride along the Columbia River and through the Gorge on the Oregon side. It is one of the most scenic rides anywhere in the world.
Some say they prefer the Empire Builder on the Washington side. It has its merits. However, the Builder passes through the area in the early evening when, this time of year, it is dark, going east. So people miss it for half the year. The Pioneer, however, traveled the Gorge in daylight in both directions on its regular schedule, which means the scenery could be enjoyed anytime of year. The Oregon side is greener, lusher (the Washington side is drier, more in the sun) and features several waterfalls, including 600-ft. Multnomah Falls. There are many other highlights. That its gone is a fact, but it is not forgotten--at least not by me.