There are a lot of aircrafts without flight management computers or even with flight management computers, not all have vnav. Most of your users are never going to fly an airliner in RL, but some fly GA or will aspire to PPL from the sim. SimBrief calculates and visualize a very nice vertical profile, but without knowing the distance to TOC and TOD, it’s not easy to use the profile when programming GPS units or actual flying.
There are also excellent veteran airlines and airplanes in MSFS where this would be a welcome feature.
I can make a separate post.