The point is you got these statistics from that ridiculous wall of text Bethesda used to try and justify paid mods. They also blamed mods for Oblivion getting a "M" rating and thus making them lose millions of dollars when the ESRB specifically stated it was the "mutilated bodies," "excessive gore," and "demonic symbols" they somehow missed in Oblivion gates that made them change the rating. The ESRB mentioned modding could add new advlt content, but that can't be considered in a ESRB rating if it's not in the base game.
You'd have to be an idiot (no offense) to believe only 8% of the PC community has used a mod for Skyrim. Honestly. Just look at Nexus Mods and Steam Workshop. The number of downloads for the most popular mods is astronomical. Just look at SkyUI to get a sense of how many people mod their games.
I'd buy BGS games whether mods were available or not. However, modding is a major factor for buying these games because it provides unlimited, free content that expontentionally increases the lifespan of these games. Much of the popularity for BGS titles, even on consoles, is because of the amazing mods that have been released over the years and many of which BGS incorporates into their future titles. Half of the new graphical improvements added to the Creation Engine for Fallout 4 are in direct respose to the Enhanced Natural Beauty mod and all the various graphical enhancements it made to Skyrim.