The 3 problems you mentioned are a definite hit in every case. I play chess with a friend by e-mail but there is no cards or dice rollings. I have thought on that topic, ( e-mail boardgaming ), the possibility to bring live webcam dicing maybe would eliminate problem #3, but for the remaining two...!?
Vassel engine gets rid of the problems but leave one running and it is time availability. while e-mailing takes care of that. Not everyone is available at all time. Family, work, etc. take big chunks of weekly time.
So, i'm with you on this e-mail play, but the problems remains. For now.