It's definitely bad if ultra-low frequencies take away a significant amount of the power from the rest of the mix. However, that only happens if they are in fact as loud, or louder. If these frequencies fit in principle well in your material (i.e. not just rumble, but nice rythmic sub-punch) you should not kill them completely, rather just push them well below 0dB so they won't trigger the mastering compressors too hard, then they can still give a subtle bit of extra-feel on subwoofers that handle these frequencies by way of rogue power, but your mix will also sound good on less capable speakers.
There's another reason not to cut the low-end too sharply: filters with high Q-values always cause some degree of "smear" in time/phase space, which has stroger consequences in the bass range than in the mid/high domain.