It is worth buying the fly more combo even if you do not use the bag, however don't rule out the bag. Its useful to store the Mavic if you do not plan on using it for a while and its actually pretty good, I put a couple of peakdesign widgets on there and use it with a better strap more often that I thought I would.
Then lets do the math....
$1000 for Mavic
$1300 for Fly More and Mavic
Difference is $300.
For $300 you are getting 2 extra batteries along with the bag. Batteries are $90 each, so $180 for 2. $300 extra - $180 for the batteries is $120 extra
For $120 you are getting the bag and the hub.
$60 for an aftermarket charge that actually charges 3 batteries and the controller at the same time (unlike the hub) so that leave $60 for a bag.
You have a _HUGE_ range of great bags for $60. I bought a nice sling back pack for about $40. So now I have a better pack and charger and $20 in my pocket.
Better off with the combo pack if you don't use the bag?
$20 in my pocket while all my batteries are charging says, nope.