Maybe. More asset classes shouldn't hurt, although at some point they may not help much (new ones may be highly correlated to some combination of the previous ones) and lower fees are nice. For bigger portfolios WF's single-stock approach may add enough value to compensate for these. I'm sure both companies have simulations proving they're better...
So with that logic, shouldn't Betterment with its 12 asset classes and 0.15% fees for >$100k invested be more optimal?