The WM store I frequent most has just remodeled. They have reduced the "boat parts" section by quite a bit and expanded the other stuff like diving equipment, SUPs, clothing, fishing gear, etc. The clothing and shoe dept. takes up about 1/4 of the store.
All the "other" stuff is the majority of the store now.
As previously pointed out, there is only so much "boat stuff" on the market. In the area of the WM store I frequent most, there are 3 marine supply stores almost within sight of each other that sell pretty much identical items. The distinguishing feature of WM is that they sell all the other stuff (clothes, fishing gear, SUPs). If I want Seadog parts, West products, or Garmin electronics, I've got 3 stores selling identical stuff. The only difference is the price (and that difference is getting smaller).
In some cases, WM was like McDonalds (or Best Buy). No matter what store you went into, you found exactly the same stuff (granted some WM stores are bigger than others). This has some advantages in that no matter what store you went to you found the same stuff, but it limited what each store could do to tailor itself to the local market needs. Not everybody wants Filet o'Fish.
Perhaps WM has seen the light.