Does Inductor saturation current play an effect in SMPS design?
Off-the-shelf inductors for bucks usually only specify a maximum output current and temperature rise, and don't talk about \$B_{max}\$ or other magnetic parameters. This is for a few reasons:


A 'good' buck design usually has ripple current of 10-20% of the DC output level (it's operating well into continuous conduction mode at full load)
10-20% ripple means the AC flux swing is small (a minor loop) so there isn't a lot of switching loss
Because the AC flux swing is small, the DC resistance of the winding is the major loss contributor
Because the AC flux swing is small, the permeability loss due to DC bias won't push the part into saturation


You can very easily get into trouble using one of these buck inductors in a non-buck application (one that has high AC ripple) - the magnetic parameters are often unknown and you're stuck empirically figuring out if the part will saturate out or not, by measuring the current and seeing if you're saturating out or not.

If you design your own inductor, you'll be picking your own core and will know all the magnetic parameters, which means you can analytically determine the risk of saturation in the end application.