Why can't commercial aircraft have a wing boundary layer suction system?
Boundary layer suction systems have been considered for a very long time, since they provide significant advantages.

However, their main disadvantage, which has never been satisfactorily overcome, is their propensity to clog with dirt and biological matter. The maintenance costs to ensure the system is operational would outweigh the gains in aerodynamic efficiency.

Additionally, this is not the kind of system that could be left to its own devices (good if it works, fine if it doesn't); it would need to operate consistently because the critical angle of attack would depend on it.

Furthermore, this system would require power to operate the pumps, and it is not obvious that the efficiency gains would make up for the power requirements in all scenarios.