actually it isn't. BC is affected by BM which reduces the strength while lances aren't. Besides if it isn't a balance issue to you, fluff trumps. Marines should have easy access to lances regardless of game balance no more than Orks should have holofields.
Actually I would think orks would more likely end up with holofields than space marines getting lances. Space marines are bound by law of the Emperor to not have lances, and not only is that who they worship every day, they are the most lawful people in existence. Now I know you're going to argue space wolves, but one chapters radicalism shouldn't define every other. Hell over half of chapters are from the Ultramarines geneseed, and they don't break the rules.
Orks however make their ships usually out of the wrecks of enemy ships (as ork engineering is very sub-par). So if they got a hold of a panzee ship, and for whatever reason didn't blow it up because it iz 2 weedy fur da boyz! then they might end up with holofields. I think it would be an entertaining design for a character ship, possibly part of a campaign or as a warp-rift article.
An ork ship with holofields would probably still have shields, and the holofields would probably be just as detrimental as they are helpful (I.e. the ork ship gets a 4+ HAwloofeld save, but every enemy would count it as closing, because of the big target sign projected on the ship.)