Am generally in agreement with most on here I think.
Am shocked that you are even considering dumping them CR.
Don't know how many bikes you have but they could have years left in them yet.
I'd expect nicks like that after a couple of london rides or a hasty shave.
In short, sod how tyres look - just keep riding until you get repeated punctures where you are sure you have removed the puncturing item - then you know they are shot.
Before any ride of any great length turn the bike over and check the nicks for bits lodged in - I flick any out with the shiny non-sharp flatblade screwdriver on the swiss army knife I keep in my seatpack.
Have even been known to check tyres at lunch stops if I have been over dodgy glassed pits or gravel where there may be flints.
This practice means I get very few punctures indeed - can't remember the last one - most punctures are caused I think not by sudden piercings but by stuff gradually working its way through a tyre. Am convinced that this is what causes most punctures on group rides - if more folk checked their tyres before a day-ride we'd all be in the pub much earlier.
Keep a good eye on the sidewalls, particularly as the tyres get very old. For the above meany-method means they may go before the road contact surface is really worn through.