Lined jeans, especially the few models that are fully lined and also use stuff like Dyneema (CE level 2 jeans) are actually more protective than just about anything, they're even more reliably protective than leather. Good thick leather is still superior, but leather quality can vary hugely. Kevlar/Dyneema is always going to be strong and reliable. The issue is just making sure they stay on and don't ride up or get tugged off you.
In my opinion, for armor, the best idea is to get something you strap on under the jeans. For instance, some Forcefield Graph Limb tubes, they're flexible and comfortable and you pull them on like a sock, basically. And they're still CE level 2. For the hips, get their shorts with armor inserts and wear underneath.
90% of all accidents happen due to the human factor. Someone screws up or just is a normal half-blind primate with zero attention span. Many motorcycle accidents happen because others cause it and you have nowhere to go. At that point, you can either be half naked and get really hurt or armored up and get less hurt. Sometimes not even armor will save your life, but it will definitely improve your odds. Riding without gear is really stupid, but it's a free world (in some places) and people can choose to do stupid things. As long as you're aware it's dumb as hell to not protect yourself when it doesn't really detract that much from the experience to do so...
The ratio of old farts getting on bikes with inadequate gear and training and hurting themselves a lot is going up these past few years. And anyone who thinks they're exempt because they don't think about it is just fooling themselves... bad things can and do happen to good people. Hope for the best and plan for the worst, any other policy is just blind faith in luck.
