These weapons would have much lower drop rates then the heavy LMGs and handheld AT; plus its your choice if you want to pick up that spare MP40, you can choose to do so or keep your tommies' rifles for greater effect. I dont think a price reduction would be 'fair', because along with the fact that youd only lose out on the weapons if you let your unit get killed, but its entirely possible to come back later and pick those weapons up on another squad.
No. It just opens up the possibility that they enemy can pick up your weapons. And if the drop rates are even lower then why even have them at all? Grenadiers rarely drop their LMGs unless the entire squad dies. If the drop rate was lower then there would be no reason to have them at all, just as I said CQB weapons are only better if you have many of them.