2.8 isn't necessarily bad. Its just a matter of what you are trying to do with the camera. If you want a wide overview of the area, or a nature cam, or a weather cam, then 2.8 is perfect. If you want clear identification within the frame for security, 2.8 gives you such a wide view, it makes objects and people smaller if they are not right up close to the camera, which can make identification more difficult.
That being said, there are times when 2.8 works well. I'm going to be adding a cam with a 2.8 lens on my front porch right next to the door. I went 2.8 because I want the view wide enough to cover the entire porch so I don't have any blind spots out there, but I also know that anyone approaching the door is limited in where they can go, so they are going to be walking directly into the identification zone and standing at the door looking right at the camera. Once they hit the edge of the porch, they are less than 10 feet from the camera so from the edge of the porch to the doorbell, I'm going to get a nice clear shot no matter where they stand or walk. (And to get to that camera on the front door, they have already passed at least 2 other cameras that are set to give me good ID quality images as well.) I don't use 2.8 lenses for cameras that are pointed out away from the house. I use varifocals and tighten up the view to cover the potential entry points with enough detail that I can make a good identification. Anything that happens near the house is in the ID zone, anything beyond the ID zone is less important to me. I don't necessarily need to identify someone loitering out at the street. That's public space and not my concern. (I can generally use digital zoom and pull a logo or a phone number or a truck number if I need to, but that far out I don't get clear faces. Once they are on my property, odds are they are going to be heading for a door or a window. Those access points I absolutely want to have high resolution coverage on.
The only point on the street that I care about, is at the end of my driveway at my front gate. I have a camera pointed down my driveway at my front gate currently. The gate is 160 feet away from where the camera is mounted and it straight and unobstructed. I currently have a HDW5231R-Z mounted there. That camera is 2.7-12mm, and I have it zoomed in all the way to 12mm. It shows the gate, the road on both sides and the driveway. I'm replacing that with a bigger varifocal. The HDW5231R-Z12, which is 5.3-64mm. If my calculations are correct, that new camera will be running at almost the full 64mm to make the gate itself almost full frame, which will give me clear ID shots of anyone that pulls into the driveway up to the gate.