I don't know. The way I see it, not having that sticker or it being damaged shows that the cart has had some kind of history from changing hands over the years before you had obtained it. To me it's the same outlook as people who collect old coins. They want that rough shape to remain on the coin and ultimately it helps keep a sort of sentimental value to it.
I like your way of seeing things. Tho I have some of those games since 15 years and converted some of them.
And I see that some of them convertions should have a sticker on to be more accurate (cause they were released after 1995) so I want to correct this "mistake"
For the old ones, it's just a matter of "restauration" and embellishment (don't know if this word exist in English ^^) to have all my cards to a same level. Two of them only...
If you're just doing this to sell the games off later then more power to you I suppose but if you're doing it to collect them, then there's no real reason to slap new stickers other then your own self-gratification of having a shiny shelf of games. As you get older you might realize that in the end not everything has to be perfect.
Not for sell, that's why I want to get them to their best shape. Btw, I'm already an old thing who likes to fix stuffs so it is just to occupy myself more than to have a shiny shelf full of games.
My own game collection so to speak is mostly complete titles but while not all in perfect condition I'm content with what I have.
Good for you