Napster at the time, was used solely for sharing and distributing pirated material. There was no legal content available at all, and it was way before legitimate streaming services.

Kodi, (formerly XBMC) on the other hand, has a ton of legal add-ons (YouTube, Crackle, Dailymotion, Crunchyroll...) that enable it to be used for perfectly​ legitimate streaming. It's only when these sellers advertise and sell 'fully-loaded' Kodi setups that already include these 3rd party add-ons pre-configured to be easy to use that Kodi gets a bad name.

It also doesn't really help their cause that most news sites these days tend to be completely wrong and misleading when trying to explain or comprehend anything technical, and always try to over simplify things to a fault. They always miss the distinction between the Kodi software itself, and what these independent, unlicensed shady sellers are doing to turn them into 'fully-loaded piracy boxes' in order to sell them for a undeserved profit, and in the process tarnishing the name of one of the best developers of open source software.

The Kodi team has really been trying to raise awareness about this recently, and has always said that they absolutely do not condone the use of these 3rd party add-ons. I remember reading recently that they are currently working on new deals with content holders to even implement a light type of DRM in order to entice more legitimate content providors to create add-ons for Kodi and thus try to negate a lot of the motivation people have for using these 3rd party add-ons in the first place.

A lot of times, (especially outside of North America), people pirate content because there is no legal alternative available. This is how Napster started, there was no real digital distribution or streaming services available yet (iTunes wasn't selling music until 2003, 2 years after Napster was shut down) and home internet connections we starting to get faster and cheaper. People wanted their content without having to go out or wait for it to become available in their region and the rest is history.

It takes a while for old giants like the RIAA & MPAA to admit that they need to adapt and leave the tried and true models that have worked for them for decades, but ultimately the people dictate the way that they want to consume their content and eventually the old giants are begrudgingly forced to give in to popular demand.

It's happening again right now with all the geo-blocking and location tracking, VPN's & DNS forwarders. The people are trying to tell them that the current system isn't working, they're going to get to their content when and where they want it, however they need to. For now, that may mean using a VPN, proxy or even a 3rd party Kodi add-on, as some people don't have any legal options available to them. But the tides are shifting yet again, and sooner or later the content license holders will have to do away with these per-region and timed release shenanigans and continue to adapt with the times.

Now don't get me wrong here, I'm in no way condoning piracy or the use of these add-ons, I'm just giving my 2 cents on how perceive this perpetual cycle of 'supply & demand'.