That X needs a configuration file less and less makes it more and more important to have your monitor(s) powered on when you're powering on or rebooting a machine, because otherwise X won't be able to get the DDC information it needs to do most of that nice automatic configuration. A side effect of this is killing off BNC monitor connectors, because you can't do DDC over BNC.

(Yes, I still have a CRT monitor at home, and until recently I was using a BNC connector for peculiar reasons. I think someone told me a long time ago that BNC had better signal quality than D-SUB, although I don't know if that's true.)

This effect actually isn't entirely restricted to X, since the BIOSes of modern video cards do funky monitor auto-detection to decide which out of a whole bunch of possible connectors to light up as the text console. I think my theoretically dual-DVI video card in the office workstation has four possible outputs (through two DVI-I connectors, so not all can be used at once), and I know that the BIOS doesn't light all of them. (I call the card theoretically dual-DVI because I have yet to get X to drive both digital outs.)

As a semi-old fogy, I have to say that the advances in automatic X configuration are amazing. For someone who once had to manually stuff modelines into my X86Conf file in order to get 1280x1024 to come out just right, being able to start the X server with no configuration file at all and have it not just come up, but come up right as I want it is a definite marvel and a nice sign of just how far we've come.

(My preferred solution to the 'monitor must be on' DDC issue for X would be to introduce some sort of default value settings. Right now, I believe that xorg.conf values override what DDC et al discover; default values would be fallbacks instead, so you could say 'if you don't get better information, assume that you have a monitor with these garden-variety capabilities'. For bonus points, you could make X record the last DDC values it saw and use them as the defaults if nothing else is set.)