Sorry, my friend, but it appears that you completely missed the point. It is a work of absurdism, yes, and thus, it must be approached as such. We don't expect genre fiction (generally speaking) to be literary or for literary fiction to take us on a grand epic tale to save the universe. Similarly, to go into an absurdist work with a non-absurdist mindset is setting yourself up to be disappointed. The plot as a whole is crazy, unbelievable, yet hilarious. The character development is similarly hilarious - all the characters are caricatures. Writing style I'm not going to bother touching, as there's no way to convince you otherwise really, and to a certain extent, it does come down to taste.
As for no relevance in the modern day. Really? I think one of the points of absurdist literature in general (which, I take, you haven't read much of) is to exaggerate and poke fun at the absurdities of life. True, Candide was very much a commentary on Voltaire's time, but to claim you can gain nothing from reading it is to claim that you can gain nothing from a better understanding of the past. I recommend you give absurdist fiction another chance. Check out Russian writers like Kharms and Gogol. Check out Heller's Catch-22. Check out Venedikt Erofeev's Moscow to the End of the Line. Come in expecting a certain degree of absurdism, and you may be surprised by how much you enjoy it.
Candide: Or Optimism (Penguin Classics)