I think we're debating a few things here:
1) Is a pure wizard more powerful than a bard 1 / wizard? Yes.
In 5e, sure. In the opening main fight? No (viscious mockery is pretty awesome). In the full release? We don't know, because we don't know how multiclass is implemented. Also, bards seemed to get the most dialogue class options of any class in my EA playthroughs.
What I would say is that respeccing in this game is reportedly very cheap/easy so give it a try and if you find you don't like it you can always ditch the bard level. Personally, my plan is for wood elf rogue 1 wizard x for the 8 skills, 2 expert and extra ranged damage that sneak attack can give you when you are low on spells. And Gale has a high chance of getting a level of knowledge cleric on my playthrough.
One thing I would say about bards though is that you can't buff your own skill rolls with inspiration, so I feel like having Wyll as a warlock/bard may be better than having a bard as a main.
