Well tbh, the new symbol system actually improved my works by A LOT like:
I have full control of all my symbols since I don't have to worry messed a symbol up since it's locked in different page,
it can nest symbols too—I used to have to manage a lot of icons and painfully replace them one by one
I can just create modals/entities and then add the contents later…
…and then easily change states without redoing the contents
it's far easier to manage my assets slicing too since they're all already in a single page.
As for copying symbols, not replacing the current one is very desirable. If it's replacing the old ones in your symbols directory, there's a good chance it accidentally ruin your current design.
I do have a solution for your icon problem that I use. You can actually change the symbols' BG color without affecting the symbol's rendering.
You can do it by selecting the symbol's artboard, change the BG color, and then turn off "Include in Instances". You can also turn off the "Include in Export" option to make sure you won't export the BG color when it's exported. Here's the screenshot on how to do it:
Well tbh, the new symbol system actually improved my works by A LOT like:
As for copying symbols, not replacing the current one is very desirable. If it's replacing the old ones in your symbols directory, there's a good chance it accidentally ruin your current design.
I do have a solution for your icon problem that I use. You can actually change the symbols' BG color without affecting the symbol's rendering.
You can do it by selecting the symbol's artboard, change the BG color, and then turn off "Include in Instances". You can also turn off the "Include in Export" option to make sure you won't export the BG color when it's exported. Here's the screenshot on how to do it: