This is great news and I applaud Microsoft for their continued, and ever-more aggressive assault on malware and malicious, deceptive and coercive marketing scams - especially considering Windows Defender is included in W10 and is totally free - without any nagging screens to pay for any "premium" version.
I note Microsoft seems to be taking this a step further than other companies and is not calling these programs "PUPs" or "potentially unwanted programs". Rather they are calling them specifically Unwanted software.
I am okay with that as long as false positives are kept to the absolute bare minimum, preferably none - ever! This has been a problem (albeit minor and temporary problem) with other legitimate programs in the past where "wanted" (and totally safe) programs were tagged as PUPs.
I do wonder why, however, they are not implementing this immediately instead of waiting until March 1? I am assuming it is to allow time for developers to submit their programs for analysis via the sample submission portal. But I don't really see the purpose for that unless Microsoft is expecting many programs currently out there NOT being tagged as PUPs by other security apps will be tagged as "unwanted" software by WD. If that is the case, it will be interesting to see how many and which programs will change their marketing scams... err... schemes.