I'm not sure how many writes the Wii flash memory can tolerate, but there are some games which save an excessive amount. Take, for example, Mario Kart Wii. Now, this game autosaves so I'm not exactly sure how many times it saves, but it definitely does it multiple times in-between and possibly during races. Playing this game, it would be easy to have it save 100 times in a day, so one could conceivably reach the theoretical 100,000 limit in a few short years.
Flash memory worked for Nintendo 64 games because each game had its own chip and it would be unlikely for a person to play the same game enough to reach 100,000 saves. The Wii memory however applies to all the games you play and even extra content such as messages and channels, so now this possible limit of 100,000 could potentially present a problem sooner than one might think. I can't say it isn't something which worries me, but then again I like to worry about everything.