This is something I've wondered about, can you get a "proper" blower (i.e. not a turbo) that can work at high revs but not be completely useless in the lower range?
Of course, VAG are twin-charging to take the drain off the crank ASAP, but do twin-screw set-ups mean you can tailor the compressors to work over different ranges?
No trawling, pure question.
Yes with compound charging you can achieve that, or if its only moderate increases in power you are looking for then a single turbo would be sufficient which is why they are so commonly used by the manufacturers in the first place.
Ultimately though, if you want big torque at low rpm, you need either a bigger displacement engine, or you need low compression and big boost, and then that tends to not lend itself so well to the top end of the rev range (a boosted motor at 8krpm doesnt want to be anywhere near as low comp as you would want if trying to get 250lbft per litre at 4Krpm for example)
As with most things engine related, it will end up a compromise.