The NCAA selection committee still uses other criteria beyond just the NET. If they just went by the NET, then LSU would've been a 1 seed (they were #3 in the NET), but instead they were a 3 seed. UConn was #2 in the NET but still dropped to a 2 seed. Oregon was #19 in the NET, which would translate to a 5 seed, but they didn't even make the NCAA tournament.
The committee looks at the following when making decisions, not just the NET:
- Availability of talent (injured or unavailable players)
- Bad losses
- Common opponents
- Competitive in losses
- Conference record
- Early competition versus late competition
- Head-to-head outcomes
- NET ranking
- Non-conference record
- Overall record
- Regional Advisory Committee region rankings
- Significant wins
- Strength of conference
- Strength of schedule
So I think there are plenty of reasons to still create a tough schedule.