With any (good) technology it becomes easier to do things and we gradually forget how to do the old, more complex way. I remember power going out at a big box (forgot which one) store once. None of the checkers had any idea how to figure out how much the items would cost by hand so the store was forced to simply not do business until power was restored. Was that embarrassing? Perhaps, but who cares? They can serve vastly more customers with the systems they have now than they ever could have with the old manual way.
With a big IDE you can manage vastly bigger projects quickly than you could with a text editor and a make file. You might point to the Linux kernel but most people who work on that just touch one area at a time . With my big fancy IDE I can work on projects of at least that size and make big sweeping refactorings in seconds with complete confidence that nothing got missed.
 With the possible exception of Linus but if you're going to require that each of your devs be a Linus (or even that you have one for that matter) then you're probably not going to go far.