Because iPads don't require activation, and carrier services do require activation. The "Activation Required" message is specifically related to cellular networ

Because iPads don't require activation, and carrier services do require activation. The "Activation Required" message is specifically related to cellular networking. This could be (and I suspect very likely is) a problem with your iPad's SIM that you could check by powering off the iPad, removing the SIM and turning it back on again. It could be that there's some kind of corruption that you might need to fix by connecting it up to iTunes or even bringing to the dreaded Genius Bar. It could conceivably be some weird bug in iOS that has somehow sprung up and turned your iPad into a flat flowerpot. All of these things suck! But what it is not is Apple forcing you to "authorize" your iPad in order to let it boot up.