If you think debuffs are so lame, why do we have them at all?
Zombies already move faster in a storm and have Feral Sense. For anyone who doesn't play on Insane Nightmare with Feral Sense, this means that the environment is much more dangerous during a storm. If you have a debuff in addition that slows you down, reduces your stamina regeneration, or blurs your vision, for example, then it definitely has an effect.
I would agree if it wasn't the case that as soon as you have the motorbike you can essentially avoid all combat outside if you want to. If the slow effect were also influencing the vehicles no matter the direction, ok. The realism fans would probably have a field day on youtube, but that is part of the package ;-).
Without slowing down the vehicles any other debuffs are in the category "who cares?" Also, bluring your vision is a really really bad idea.
Though I haven't tested myself if the drift effect on the vehicles is strong enough to make that difficult enough.
The damage is a simple measure that leads you to taking shelter. It must be balanced right so you don't have to "constantly eat bandages" but drive to a POI without interruption, and then heal yourself.
If it wasn't obvious, no, I don't think you should be able to completely stay outside even if you take some risks. When you say "You'd just have to be more careful, but you could manage the situation without having to constantly eat bandages or medkits just for being outside." it sounds like you want a way to be outside for the whole storm and I would disagree to that, but maybe I am reading to much into that sentence