No, I agree that this isn't the ideal situation since it reduces a pilots situational awareness of vehicles, which I would suggest is extremely favourable in a runway safety environment. Also, as you say, it increases the likelihood of crossed transmissions when one party can't hear another, another potential safety issue at worst and irritating at best.
I expect that it's an engineering equipment limitation and that there is almost certainly a cost implication. However, all you can do is request the change and see what response you get. It may simply be that no-one has raised the issue, or at least connected it to safety enough to get a satisfactory response.
It's probable too that this situation is not solvable in it's entirety since any reasonable sized aerodrome is likely to have areas which are blind to each other, even when all areas are within range of the tower.