I always saw the plastic tip as being there simply to sucker in the shooter that these bulletrs were more slippery through the air than if the hollow point was exposed. In essense the bullets are an aggressive hollow point which will expand rapidly at high/medium speeds so are more suited to long range where the 'ballistic' tip provides a more aerodynamic shape and slightly higher BC. The slower speed at impact requires the hollow point to expand rapidly otherwise you just drill a hole through your target.
But are we shooting deer over several hundred meters ?
Rapid expansion/fragmentation is not what we want in most cases, so for short/medium distances (say up to 150M) softpoint bullets are more suitable and would cause less carcass damage.
Brass and Copper, being a harder material, need that extra energy to expand and so the aggressive hollow point is almost a necessity. There is possibly an advantage therefore in non-lead bullets by fitting a plastic pointy tip but given that instability is proprtional to length you will probably get better results by removing it altogether.