the cdi and zelda games usually ebay for over 100 bucks each. Did you seriously pay over 300 dollars because you were curious about something you heard was really bad or did you just watch the latest ANGRY VIDEOGAME NERD episodes on youtube where he reviews the same games you wrote about in your post?
I'm going to guess that second one, but if he did play them I'm hoping he just emulated them.
Also, this is true about the 3DO and is possibly true about the CD-i and the Sega CD (haven't looked into it but it's very likely that this is true), but if you can afford the system, you can afford ALL of the games, because they had no copy protection (since no one really had CD burners at the time). As long as you can find the download, you can play all the games on the original system. Possibly foreign games too, I'm not sure. So if you ever really DID decide you'd want a CD-i--although there is NO reason to buy this thing, let me restate that it SUCKS ASS it's just not the worst system ever--then make sure it's copy protection free and buy just the system.
But don't. Because it's not worth it.