I think the duplicate protection actually increases the value of drafts. Without it, you needed wildcards to get the rares you wanted. Now you can easily complete the set by buying packs. So every trash rare you draft is a pack's worth of progress towards the cards you want.
I often get passed multiple rares in a single draft, which alone pushes the value above packs from a collection standpoint. On top of that, every third draft is basically free from gem rewards, you occasionally get another free pack and your progress towards the vault increases. Of course you also want to draft a little for the season rewards, too. So basically, there is no way, packs are better value than drafts, until you risk multiple duplicates per draft.
Maybe packs are an acceptable alternative, if you don't plan to go for set completion. However, why wouldn't you? There's easily enough gold for it, even for free to play guys like myself. Buying packs gets you specific cards faster, but you lose a lot of collection value.