Originally Posted by Strell
We will need to get someone in here who knows more than me (there were two IT guys a few pages back, Lyth and someone else, my apologies for not remembering), but I'm unsure if flash and solid state drives are 100% the same thing. The Wii's internal memory was flash as far as I know, and I don't think anyone had a problem with that.
The concern for write limits are primarily in environments where data is constantly being updated and written to the drive. I've often heard people suggesting that you not defrag a SSD on a regular basis because that can result in a lot of writes to the drive. On the Wii U it isn't as much of a concern because you're primarily using the flash storage to manage tiny game save files or rarely installing a downloaded game.
Also, the Wii U probably has some hardware measures set to ensure that whenever you overwrite a save file it is not always written to the exact same location. That would evenly distribute the wear-and-tear over the product's lifespan.
... at least that's my understanding of things. As Strell mentioned, maybe a tech person can shed a bit more light on the topic.