THAT fits how I feel very precisely, IF I had been able to articulate it so well.........So, when you buy a Ruger, you get a gun that works as intended by the manufacturer, and as was pointed out is going to err on the side of safety and function rather than fine finish and match-quality smoothness. You buy a project that is solid from the start and can improve upon it as you wish...........
A LOT of folks are happy with them as-is, "out of the box," but I personally have experienced one REALLY nicely tuned Bicentennial model Security Six a long time ago, and ever since have not been satisfied until I've achieved that level of tuning on any others I've owned. It's fussy work, but it's worth it and I know what to do, how to do it, and just how much to do with the 'Six series/SP101s and am certain I could figure out a GP100. So, I am partial to them.
I'm guessing the GPs are very similar in that they provide the buyer a certain level of opportunity to "improve upon" easily and to a level which suits them. I don't see that as a negative personally, I see that as letting me make it work as well as I want it to work - like buying a good axe and tuning the grind to suit my uses and habits. If a fella's happy with the way that axe works right off the shelf, it's a win-win.