There was a trend toward designing reamers very closely to virgin brass dimensions for a few years, some time back. For the most part, people finally got away from that practice because it created sizing issues and, as you alluded to, clickers, without any real upside. I think it's the main reason there is a market for custom dies at all, other than wildcats etc. I think this was an example of trying to be "too perfect" and causing problems rather than being better, per se. Like women, brass is only virgin one time.
Lol! You don't want too much but I'd much rather have a chamber a tad too big than the other way around and dies really do more to determine what is the ideal chamber size than anything else, imo. For a PPC or Grendel based case, I want no smaller than .442@.200 line but you can certainly go a little tighter if you buy custom dies, but there's just no reason to go tighter than that, IMHO. That's just my 2 cents and it's not the only right answer. Plenty of examples of both tighter and more generous dimensions working well.
I actually prefer to spec the reamer around available die dimensions rather than virgin brass. It works well and doesn't necessitate custom dies. I've seen die makers modify die dimensions slightly over the years but this dimension is generally a pretty consistent number to work from, where as we've seen lately with different brass, the brass can be quite different at times. Again though, more than one way to skin this cat and I've never seen a difference in how they shoot, either way, until you have clickers or at the other extreme, primer pockets not hold up quite as well.
