I actually find the use of the steering weight as "necessary" and here is why. From delivery day and several weeks after, I kept getting the message to apply force...but...I was! My hand was on the wheel, slightly pulling it depending on the placement and yet the nagging message kept popping up. Another owner suggested I get one and that it would solve the problem...and it did. I hardly notice that it is on the steering wheel and with my left hand on the wheel, I no longer get the warning message and I feel as if I am actually more attentive than dealing with the popup messages.
Someone mentioned airbag deployment issues and I would argue it isn't in the way and likely not going interfere. The model I have uses two very sturdy magnets that are aluminum welded, not glued. I am sure the forces in a sever accident may cause the unit to separate but given the location, I doubt it will do anything to obstruct the safety systems. Pretty sure other junk, mobile phone, water tumbler, etc. will do more harm...just saying.
Use it in an "assisted" manner while still having one hand on the wheel.