What bad are you referring to? I don't know what other side you're referring to but being able to read, write, have an Internet, have cures for diseases, are pretty good. So what bad side of the Enlightenment is relevant to our lives?
To me and in my opinion, rationality is what makes us human. It's our ability to reason at a very high level due to our neo-cortex and frontal lobes which make us distinctly human.
As far as "dangerous" goes, dangerous would assume there is an agenda to keep people ignorant? I suppose I am dangerous to that because I don't desire to remain ignorant nor support any agenda of involuntary ignorance. If self empowerment makes me dangerous then it's the justified kind of dangerous, or at least justifiable to an individualist. Individualism simply means to think for yourself. Rationality, simply means to protect yourself to the best of your ability, to do what you can to give yourself a good life, or a comfortable life, if you desire to have that, and to even improve your environment and those around you so as to have a greater probability that your future self will have a good life.
My intentions for supporting the idea of anti-aging? I'm not enjoying getting old, and would prefer to slow it down. If anyone else feels the same way about that then let's pool our resources toward slowing down a process none of us desire or enjoy. Yes it's very rational, and if you're looking for an ideologically relevant interpretation then you have ethical egoism, you have egoist anarchism, both which inevitably will lead to the same conclusions on anti-aging for those who don't like the idea of getting old.
Rationality is a means to an end. Rationality is useful because it's the key behind effectiveness in whatever it is you do. If it's altruism then effective altruism is simply rational altruism. If it's survival then effective survival most of the time is rational. If it's medicine then evidence based medicine tends to be rational and tends to produce better results than belief centered medicine.
Anyone is free to live their life how they choose. I'm not someone who wants to force or demand anyone become rational if they don't want to. Nor do I demand people give up their beliefs even if their beliefs are incorrect, wrong, ignorant, or proven false. I do not have any fixed beliefs myself, so I'll have to admit that I don't and that anything I believe right now will be completely changed no matter what it is, if the evidence guides me to change it.
Shall I remind you the main events of the 20th century?
And without rationality, without a new Age of Enlightenment in a decentralized global context, what makes you think we will be able to avoid the possible trajectory with AI being abused by some of the most ignorant people?
AI can be used to help people or not. But I don't think AI is going to automatically be used to help people if people don't save science. Philosophy is important as well and as I said there will be residual effects of augmenting the rationality of individuals in that you'll get more effective ethics.
We already see some of this actually but not enough.