Actually I prefer it to do so - when I get on an aircraft or coach I point the vent at me and open it. Thst's why individual vents are a good idea as I can choose to have it and you not.
@LSWR Cavalier's view seems to be rooted in the idea that you catch a cold (and other respiratory illnesses) by being cold. You don't, though being
really cold for extended periods (e.g. camping in bad weather) can cause a bit of immune suppression. The reason respiratory illnesses like cold weather is the effect of cold weather on behaviour - people move indoors and shut windows and doors, which means the virions aren't blown away and hang around to infect people. Plus virions survive better in slightly cooler temperatures; high heat kills them off (hence why we get a fever when infected with a virus).
I don't know about 80x but on most trains the crew have no control over it. Pendolinos are one specific exception where they do.