Linguistically, I can see the arguments on both sides. But to me, the much lower level of tongue dexterity required to speak the three-letter version vs. adding

Linguistically, I can see the arguments on both sides. But to me, the much lower level of tongue dexterity required to speak the three-letter version vs. adding in the r is substantial. To be clear, I'm not actually advocating for it in the context of contemporary cultural norms and slangs. Objectively speaking though, one is physically a much simpler movement to speak than the other, much closer to the physical simplicity of "bit". I readily notice this as someone who stutters and underwent various speech therapy as a child, then later in life lost three upper incisors to a car accident and had to retrain himself how to pronounce certain sounds. Not saying that should be a dominant coefficient in the evaluation, just that physical reality is something to consider and acknowledge with some nonzero weight.