I think the costs and legacy barriers are completely fair dev team. Please, please, please don't listen to the whiners and lazy people.
After buying the all the class XP boosts, I'd like to give my feedback.
Mainly, I was hoping for a bigger boost but after thinking about it for a while, I think it's fair. I read an interview somewhere in which a dev said "yeah, you can only do your class quest if you want" and I imagined like a 300% XP boost. HOWEVER, I realize that his statement CAN be true, but it's just not what I envisioned (and for the record, I am fine with this). If a player buys ALL the XP boosts, then yeah, that player could ONLY do class quests on planets. But, class quests cannot be the only source of experience income. The 30% simply isn't enough (I've tested it on the PTS with lower characters). The player must also dabble in PvP, FPs, exploring, space missions, and perhaps companion quests to compensate for ONLY doing class quests.
While I was slightly disappointed, I realized that this was fair and more feasible for everyone. Legacy perks should NOT grant an insta-50. It is designed to make leveling an alt faster, which it clearly does (maybe not as fast as someone would like but it does). The prices ARE reasonable. Buying them all at once is a little 'ouch', but with the consolidation of the GTNs and higher populations across servers, I believe with confidence that players will see more credits in their inventories.
Look, it's OK to hate the system, it really is. There is no One True Way the Legacy system had to be designed and don't let any game designer, real or armchair, tell you otherwise.
For example, Legacy could have worked like character skill trees work, where you can choose which perks you want to turn on for your current character by moving legacy points around. And a credit sink could be added so that you can reduce the legacy point cost of some perk for all your characters. Now, imagine the nice surprise of logging into an alt you haven't played in a while and seeing "You have 25 unassigned Legacy Points" appear on your screen, then going into the Legacy screen and picking the perks you think would be fun to have on this alt.
The current system works well for some people, but because it can never be perfect for everyone, there's always room for improvement.