Exposed bicycle chains are absolutely cringeworthy and should only be reserved for racers. Your chain is a pretty much an open bearing and should NOT be exposed to the elements, it should be encased in an oil-bath, unless you ride in a super clean environment. Normal people should not use exposed chains because they don't clean their chain like they should, even most amateur racers don't clean their chain as they should, thus drastically reducing efficiency and the lifespan of the whole drivetrain, increasing the costs of maintenance !! Sand and grid gets stuck into the links even after a small ride !
If you want to ride without a chaincase you MUST use a belt-drive. Other wise you are falling for a ploy to make you pay more.