Well, the legendaries in the shop aren't going to remain static, so maybe there'll be some cheaper ones later.
Given how the faction guardian and empowerment systems work, it's hard to imagine I'll ever have enough spare legendaries to make "unbinding" worthwhile. Maybe if it turns out I'm the rightful King of England I can trade the Crown Jewels for enough sacred shards to get another 2000 tokens, but otherwise it's not going to happen unless I'm still playing this game at the age of 900.
I'm hoping Plarium hands out some life tokens periodically as patch gifts, tournament prizes, and so forth. Otherwise the only people who can actually afford to use them will be oil barons and the House of Grimaldi.