Some good reading in this thread - sorry I'm late to the party.
A couple of thoughts to add. Bear in mind that I'm coming to this from a starting assumption that it would make sense just to have straight 4* gaps through the irons - which is what I believe was the "traditional" (as in pre-1970s) standard, and also that I know the way in which short iron lofts have been squeezed by manufacturers for "extra" distance.
First point. I have some "classic" era sets of irons - Mizunos and Hogans. In both cases, there's a loft spread of 30 degrees from 2i to PW (ie 8 gaps). Regardless of what loft you set the PW at, it would still have been possible to cover the gaps between clubs in a much more evenly spaced increment. So, I'm inclined to think there's more to this than simply "loft creep". Both sets have a 5* gap between 9 and PW (and a larger gap between PW and SW), 4* gaps through the other short and mid irons, and 3* between long irons. Between 2 iron and 1 iron (should you want to go there) - you'll find only 2*, at least with Mizuno. You might think there's some logic to that pattern - smaller gaps between long irons, larger gaps between shorter irons. Both companies could have gone with much more even gaps (and Hogan lofts were stated to 0.5*), but didn't. The question is why?
Do changes in loft have a more pronounced effect when loft is lower? (assuming you have enough clubhead speed to launch the ball properly).
Or is it easier to finesse in-between yardages with short irons?
Second point. Supposing you don't like the gaps in your current set. Is it straightforward to adjust them? I don't mean physically - I have a loft/lie machine and it's no problem at least with forged irons. I question whether the weight distribution designed into an iron is specific to the intended loft. I think, when you bend a club weaker, at the same time you are lowering the CoG. I bent my Hogans to 4* gaps, and I bent the 2 iron 2.5* weak and the PW 2* weak into the bargain. The long irons became (duh) much easier to launch - but I also found some clubs that I felt ballooned ridiculously. Could have been me - could have been a flip. Or maybe there's a limit to how far from original spec you can depart before the dynamics of the club are dramatically impaired.
I've just bent my Hogan's back to original spec - and will see how I get on. Obviously, I'm expecting to see extra distance out of most irons - but I'm curious to see whether I have a "better" ballflight.