I keep as many games as possible ( my parents used to throw them out). Honestly I'm one of those people who have games they've never played but can't give them up (mostly because stores aroud here won't uy a game for mere then $5 if it's older then 5 years).
If you can make a significant amount of money of them then I'd say do it, nothing wrong with money that could be used for something else. But passing them down isn't all that bad of an idea, in 20 years though will some of these be worth more or be over and done with and sell for a few cents.