Why? Because you can! And pickle, and jam, or otherwise celebrate the resurgence of the domestic arts our forebears held so dear. Put on your best apron and step into our kitchen, won't you?
Your seedlings are growing well and will soon need a new home, i.e., a bigger pot. Here is how you repot with minimal trauma.
So you've planted your seeds and the first leaves have appeared. They are most likely two nice, round leaves. These are the 'seed leaves'. After you have two or three true leaves, you need to pinch off the seed leaves.