So how about them new dungeons? (Layout and difficulty)

[Shurrikhan]

Absolutely correct stuff.

And yet...

Some designs really do pay off more than others--often by what seems to be coincidence, often by principle, and often just because they give something conceptually new to their base (even if not necessarily great or new in itself). Movement towards more interesting dungeon designs might cover all those points, and may well end up with a better payoff. Given this particular team, I doubt it, but with another that's probably where I'd lay my bets.

If my choices were several dull options vs. one more entertaining one, I too would take the singular but superior path, I just don't believe the development balance is necessarily quite so simple or rigid. Hell, if we'd built up more interesting mechanics across our railway dungeons as is, at least we'd have a whole lot more to throw in later if we ever did take a different design path.