I don't think we necessarily need a high volume of "deep" passes to boundary WRs. But we have almost no passes to boundary WRs that aren't within 5 yards of the LOS, and when we do throw 10+ yards to a boundary WR during any time this season that wasn't the 4th quarter of the Ravens game we've had little success.
It's a problem, because it allows defensive coordinators to clog up the middle and stop the run and basically dare you to throw to the outside. The Texans did this masterfully last season. The Bills answer to this has been to have long 10+ play drives with many first downs in order to score a TD. That gives almost no margin for error, and a single negative play or penalty kills the drive. Being a well rounded team is important so a good DC can't just take away what you are good at.