You see, I think its worthwhile you going back and looking through your old images. Not to see how you have improved, but you never know there might be an image that at first you discarded and now you realise that image has got something. Furthermore your editing skills may be better or you may have a new plug-in that will give that image what was missing from it before. Don't get me wrong a bad image, can never be made a good one!
But, looking back at images will also brings back memories. Memories of the places and the people you have met. Maybe you had a quick chat to or just a candid shot that you were pleased you had captured.
For me looking back at my old images I hadn't realised how many street photographs I had taken. Street photographs, that is, with people in them! Oh yes I went through a period of just taking the abstract of a building or a treelined street or the flowing river under the bridge and cropping cars and traffic movements out, I still do that from time to time. But some will say that real street 'togging, is with the human element, and that's what I really enjoy and now looking back I've always have.
So give it a try check out your old images. See if they can be enhanced better than before with your new editing skills or programs. Reminisce over the photographs and enjoy them. and above all never DELETE them.