Kodi make it very clear that Addons that access pirated content are NOT supported - so I think they are in front of the issue of piracy.
However as an Open Source project users can still do dodgy stuff - but I don't see this as Kodis fault much the same way me driving my car drunk is not Holdens fault.
And as for Sky claiming each box is equivalent to a lost Sky Subscription....ppfffttt.
And as others have said while I have some addons installed, it took me years before I bothered and I only use them intermittently - and Kodi for me is ALL about organising and showcasing my locally stored content.