The biggest reason, in my opinion, has been the invention of anti-viral treatments, that while they don't cure the disease (HIV), they halt its progression into AIDS. HIV was for a long time, a literal death sentence and carried a cruel stigma as well.
Plus, initially, there was a media circus surrounding it. People didn't know exactly how it was spread and even worried about mosquitoes transmitting it. Also, there wasn't a distinction made between HIV/AIDS, for the common person.
However, as time has gone on, we now understand much more about he disease and have seen people living with HIV for decades, most famously Magic Johnson.
At least in the mind of the average person who has access to modern treatments for it, HIV/AIDS is no longer the boogie man it once was. That said, it still ravishes many lives and I hope that it remains a priority to develop a cure.