Camber plates are not necessary.
Similar adjustment can be achieved with camber bolts for less money.
If lowering for looks only or mostly, no need for camber plates.
Camber plates come into play if you place premium on handling.
2 reasons.
First- You can dial in your adjustment, more negative camber for bite on turn in.
Second- A camber plate is a metal top mount, like a ball joint, so there is no deflection of the top of the strut on turn in, resulting in more responsive and precise steering.
You decide.
Looks, or you like your car to handle and have responsive steering.
On springs.
Your decision and budget again.
I don’t know that you’ll notice much difference between your SR springs and Eibach.
You’ll have to try to find out.
One advice, being a 22 year old car, if you do rip out your struts it would be good maintenance and time to replace your old strut mouts.
The rubber bushing in there must be past its shelf life.
So, thinking like that, if you do decide to replace strut mounts, the money you would have to spend on those plus possibly camber bolts would go a long way toward paying off the camber plates.
BTW, camber plates replace the strut mount completely.
It’s not one plus more money for the other.