I would suggest that, if such grenades are generally available, and are useful, TL14+ battledress will either be even rarer issue than it already is (because it's damned expensive and only useful against under-equipped low TL opponents), or will have better levels of protection.
I don't see what's wrong with TL-14+ battledress, the cutting edge of personal protection, requiring support weapons to take down (though in MT shooters can do it with ordinary small arms anyway with good tactics, luck, and/or high skill). That's the point, really.