Hi Bob,
I think Niall Carlton's post probably captures things about the early Muirfield most accurately, but I simply think some context is needed to help us frame the changes to the golf course from a historical perspective.
Before 1892, for 31 years the Open rota consisted of three courses only; Prestwick, St. Andrews, and the 9 hole Old Musselburgh links. When the HCEG decided to move from Musselburgh to Muirfield, that was bad enough for the Musselburgh men. However, when it was HCEG's turn to organize the Open event, their decision to also move the hosting venue from the Old course to the new one was greeted with shock and dismay in Musselburgh, and among many competitors.
That event was also played for the first time at 72 holes, and when that event was won by the amateur Harold Hilton, cries arose that it was only because the golf course was too easy, and not a true championship event.
Much of the dissatisfaction, as well as comments such as the "Auld Water Meadie" by Kirkaldy also may have been more attributable to the raw (and muddy in spots) condition of the golf course than any architectural issues. The course itself had only been built in the spring of 1891, open barely a year by the time of the 92 Championship.
Against such an outcry, and with a limited rota (although Royal Liverpool and St. George's were admitted the following year) the club knew it had another event to host shortly by 1896. The club assigned Patrick Don Wauchope to oversee changes to toughen, and seemingly most importantly, to lengthen the 5,200 yard course.
He certainly seemed to accomplish the latter goal, adding almost 700 yards to the 1891 layout, as well as reformulating bunkers, etc. Perhaps his chief lasting accomplishment was the creation of an early form of today's 9th hole, which he accomplished by combining Morris's original 14th and 15th holes.
For how highly Hilton praised the changes however, you would have thought the re-routing might have been more extensive. Instead, here's a summary of the 1896 Wauchope routed course compared to the 1891 Morris course;
Hole 1 - Same
Hole 2 - Same
Hole 3 - Same
Hole 4 - Same
Hole 5 - Morris 8th
Hole 6 - Morris 9th
Hole 7 - Morris 10th
Hole 8 - Morris 11th
Hole 9 - Morris 12th
Hole 10 - Morris 13th
Hole 11 - Combined Morris 14 & 15
Hole 12 - Combined Morris 16 & 17
Hole 13 - New
Hole 14 - Shorted Morris 7th to Par three
Hole 15 - New
Hole 16 - New
Hole 17 - New
Hole 18 - Same
In any case, the Wauchope work seemed generally well received but some of the early stigma and criticism stayed with the course, particularly after the turn of the century brought the new Haskell ball, leaving the land-locked Muirfield struggling to find room to expand.
To understand this better it's important to note that the land originally used by the club for the Morris/Wauchope course did not include the land where today's holes 3, 4, 5, 6, 7, 11, 12, and 13 exist! Further, not only were the western, southern, and eastern boundaries hemmed in by stone walls, but at the time so was the northern boundary, the remnants of which exist today on the left side of the 6th fairway.
In 1909 the club was able to purchase an additional 13 acres in the northeast corner of the property allowing them to expand their 8th and 10th hole while creating a new ninth, but it wasn't until the 1920s when the club accumulated some additional 50 acres to the north that today's course became possible.
So I think the combination of blowback and resentment from the Musselburgh decision(s), the immaturity of the golf course to host the Open a year after opening, and the quickly evolving technological standards such as the Haskell ball all conspired against the Muirfield reputation. After all, how many courses built before Haskell weren't similarly affected, yet most didn't have to live in the spotlight of the game's most important championship during those evolving years. The early stigma, fair or unfair, stuck with the course as seen in this March 1912 article;