What are their purpose? My last 01 accord I did the brakes and I think I left them off when I put it back together. Now my 99 needs brakes bad and I am sure those hard to get small screws on the rotor is a chore to get off. Any hints to getting the stubborn ones off?

 

They are unnecessary.

 

In theory the rotors are held on by the lug nuts so they hold close to the hub but I've always used them and I feel like I have less brake pulsation issues when using them. You can use an impact screwdriver to remove the screws. I went ahead and found a vid from youtube you can use to get them off after buying the tool

 

If you use a JIS screwdriver they come off much easier. And they are not at all hard to get.