I personally don't like the shift, even being in the younger crowd. Calling someone by their first name sounds not only presumptuous but leaves you in an awkward spot of guessing whether to use a nickname (you may heard they've been given) or their full first name. With some coworkers, it's fine 'cause we're on a friendly basis anyways, but if I don't know from Adam, I prefer people don't use my first name. It only lowers my respect for them.