It's unwise for them to not offer paid sick leave because, if you go in to work sick, you make everyone else sick, which increases the number of people who can't work, even from home.

My employer gives 8 hours of paid sick leave a month, which accrues indefinitely. If you don't take it you keep it, so if you have a major illness, you can take extended time off without having to go into FMLA or short-term disability. I don't know why all employers don't do that. Requiring you to use annual leave for illness seems chintzy, to me. :(