The reason I started looking at the 325wsm is that the particular rifle I'm interested in, isnt offered in a 338wm mag any longer. I dont have any big issue with not owning a 338wm and its balistically similar (not identical I know) enough that it'll meet (and exceede) my needs.
Im kind of excited to have a new whiz-bang calibre. I dont think you can fault anyone for just wanting to have more toys to play and experiment with.