I don't recall ever suggesting that qr objects should actually be interpolated. The only reason I ever interpolate those is because I can write the original regex without having to go backwhack happy on \s and friends. There's also not much point in interpolating qr objects because you get bit for compiling that bit more than once anyway. But you knew all that anyway. *grin*
But given the nature of qr, I don't see why you'd want to keep stables of them around just to interpolate them anyway. The whole point of a qr object is that it is a complete regex. Also, once that complex regex is parsed all the frippery is thrown away anyway so it doesn't really change runtime performance. So I don't think you've said anything about why not to use qr. You just stated that it isn't useful to keep qr objects around if they're just going to be interpolated back into other expressions.