"B people are too cheap they kill you"
That is literally the point of the game mode, eliminating all hostile hero ships. Don't fly into the enemy team head-on, try to outmaneuver them, or try sticking close to an ally.
Levelling multiplayer content offline would be unfair and pointless. That is not "fixing" anything, it is making the mode unnecessary.
If they were to allow offline levelling, then the game might as well present us with top-tier cards and max. level ships from the start. All online content is upgraded through online activity. Of course there will be times when players feel like they don't stand a chance, but that is how all multiplayer games are. BFII is pretty casual, it is not that hard to find matches where you can get decent scores.
But if you really want to make a suggestion, at least make it more viable to the multiplayer environment. Making the Hero Starfighter mode more alike to Heroes vs Villains would be perhaps a good idea for people who find the current system too hard. Allowing Hero Ship respawns and having a Target system instead of a full-blown Team Deathmatch could be considered.
But I'm pretty sure I've written the same response to a same topic long ago...