IANAL but my understanding is that while practically speaking the war is lost for SNES, corporations have to be seen to be defending their IP (particularly game characters in Nintendo's case) otherwise they run the risk of it becoming public domain in the long term. An example of this is brand names becoming generic names (e.g. dumpster, chapstick, escalator...). The corporations that owned these terms lost control of them because they weren't able to do enough to defend their IP. Since many of their modern titles are reliant on old IP it is vitally important that they retain a grip on it from a legal standpoint.
That’s specific to trademarks which don’t automatically expire. Copyright and patents are mostly enforced via lawsuits, but in theory are in full effect until the clock runs out.
