If Google was to enable calendar syncing they would have to pay Microsoft for the priveledge, by licensing the ActiveSync protocol. Just as Apple does for every iPhone they sell. But, Google has been able to foist that on their OEMs and Carriers, so either HTC or Verizon foots the bill instead...
Playing the platform game. Same way Microsoft used to not box a DVD codec into Windows because they didn't want to pay MPEG for every copy they sold.
But, it is annoying enough, between the paltry 4GB default microSD card that I'll have to pay $60 to upgrade to the lack of exchange support now someone wants $20 to upgrade (and not natively), the lack of multitouch support (so they don't have to pay Apple royalties if they come after them on IP), that I may just return my new phone and go back to the old iPhone.
Google, just charge $599 and make the phone awesome out of the box. You would have sold more, not less, if you'd done that. Geez, you'd think a bunch of PhDs could figure that out.