I use sticky post on clients' sites regularly, to keep a major / urgent / vital information at the top while still posting other stuff (including featured) without playing shenanigans with publish dates or featured articles/sliders, etc. My clients need and use it regularly. It can also be used for reminders. About half the time, I use it with the "aside" post format or an equivalent. I'd miss that feature a lot if it were to disappear. To me it's absolutely not the same thing or function as the "featured" posts. Two functions, different uses.