Yes, but other 4 men squads are elite infantry that are supposed to be vulnerable, and not the mainline infantry. Obviously 5 and 6 man squads can be oneshot by explosive weapons too, but the chance of a full 5-6 model wipe is signifcantly lower than with the 4 men Grenadiers.
I guess so... I don't really think this is an elegant fix to what the perceived problem is, but oh well.
I think this change will punish small explosions over the big ones, and as a result make teching nades an even less appealing option.