Biovores

Generally just lack of space for them. They certainly are excellent, but Tyranids tend to suffer from 'it would be great if I could spare the points by I need more anti-tank or whatever' syndrome. By the time we fit in all of the anti-vehicle and troops we need, there isn't always room for things like Biovores, but when there is they're great.

they're a little more useful now that barrage is basically a precision munition; but it's a S4 AP4 blast. we already have tons of way to smash infantry.

I'm going with giga there. I love to field mine, especially against a GEq heavy army, but we already seem to have so much anti-infantry that I'd rather have the points somewhere where it can hurt vehicles.

One thing to consider is that Biovores are your ticket to first blood. Mine have wiped a small unit on turn one several times. For that one extra killpoint alone I think they are worth the points and the slot.

I think they still suffer from 5E. Then we needed anti tank, so Biovores just could not make the cut.

I think 6E helps to make some room for them.
There is more foot now, Barrage can be used to snipe out characters or important models, aim them behind those ADLs and avoid that 2+ cover save, more terrain makes them easier to hide and they don't need LoS.
Plus, from what I keep hearing, many Xenos armies are making a comeback, so their AP4 starts being much better.

Plus, they are pretty cheap.

Well, you can always use that pyrovore model you have wandering around. Makes for a better looking biovore too!

I think that why you don't see so many on net lists, is because most net lists are optimized for tournament play. And as others have already said, almost everything in our army kills infantry. So most tourney lists are optimized for killing tanks and transports.

If you look around in LGS's and kitchen gamers lists, you'll see a lot more biovores.

I take them in about 70% of my lists.

The benefit is that you have a 48" range. This allows you to start killing off the enemy models before you get close. Otherwise, they will average 2-3 rounds of shooting on your troops before you get close enough to assault. Then your assaulting their fresh units with your wounded units.