I like having the ability to "collect everything" without having the pressure of knowing that if I don't go online or visit a particular store/promo within a limited time span that those items become almost impossible to get without either a cheat device and/or an online trade partner. This applies even more so to the Wii version since those "online exclusive items" aren't preprogrammed into the game to find with a cheat device if you do miss them.
As for the GCN version... I haven't played the GCN version in probably a little over a year now. But that has more to do with the fact that I have beaten/completed 100% of that game. At least 100% of what is humanly possible without a cheat device. I managed to get several e-Reader cards and make special memory card "train travel" trades with people personally from other GCN towns to get all 15 station models. Through Guyute's help I was able to obtain the e-Reader cards for the e-Reader exclusive NES games (Ice Climber & Mario Bros.). I also (thanks to Animal Crossing's passcode system being "universal" despite the game's release region) was able to get the NES game Punch-Out!! (never made available in the US), as well as Donkey Kong Jr., Donkey Kong 3, and CluClu Land D thanks to contest codes from Nintendo's UK Animal Crossing website (much like how I got a contest code for Soccer from Nintendo's US Animal Crossing website). I even managed (after nearly 1 1/2 years of buyng 500,000+ bells on turnips and selling them on the stock market on an "every week" basis) to save the 999,999,999 bells needed to get the post model.
Only thing I'm missing from the GCN game now are the 2 "non-catalog/cheat device only" NES games (The Legend of Zelda and Super Mario Bros.) & the 8 "removed/non-catalog" shirts (plum kimono, blue sweatsuit, etc.) that are impossible to get without a cheat device or by hacking the Nook trade passcodes.
Oh, and my physical set of eReader cards for the GCN game are no where near being complete if anyone is wondering about those.