The primary function of a rear light is to get you seen from the rear. I'm not saying that having a rear light that has more side conspicuousness isn't going to be helpful but in my opinion I want vehicles approaching from the rear to see me "sooner" rather than later. If you want to be seen from the sides better there are many other ways to do that that don't require a specific rear lamp.

My approach to being more conspicuous from the sides is to first, use more lights in the front ( including a small helmet light ). Along with my main bar lamp I also use a small flasher down on my front fork. Of course if you use wheel lights and / or a helmet light on flash, any one of those will get you well noticed as well.

Actually though the Hotshot 150 is fairly conspicuous from the sides. I could provide photos that show this but unfortunately any photo ( or video ) of an LED lamp will almost always make it look brighter than it actually is. That said here is a photo taken above the seat of my bike. Forget how bright it looks. It's not actually that bright. More importantly, notice the beam pattern how it stretches beyond the seat. Just believe me, you can see the light at night when standing in front of the bike ( ten ft. from the front and then 10ft to the side. No it doesn't look like a ball of flame ( like from the rear ) but you can see it.