The 'one iconic ability' that each class has and can be inherited via the legacy system allows for abilities that are not normally available to one faction to suddenly be present, does it not?
For instance, I have a level 50 Bounty Hunter. If I now role a Jedi Consular, that Consular now gets access to the Bounty Hunter's flame thrower during any Heroic Moment use. As far as I know, there is no flame thrower abilities on the Republic side at the moment.
Not that this is overpowering, considering the limitations on use, just that it will be sort of odd.
How is that rock you live under? This has been addressed over and over. Essentially BW has said if you're an alt whore and have 8 lvl 50's (one of each class) your characters will have all heroic abilities. They even came out with a discussion video of how it "fits lore" because of anikan, having luke and leia, leia marring a smuggler blah blah blah.