Even if they were super rare I think skills are already cheap enough as it is (way cheaper than they should imho). We already have mission rewards, I would rather see something completely new introduced that another way to devalue our avatars.
Plus with all the skill pills it is really easy to skill up. I don't see it mate
With the deflation of skills over time and so many people reaching the 'upper limit', it would be crazy to add full skills as loot, which would further saturate the market. I would be happy seeing a few more ESIs in loot. From personal observation it seems like there was a great reduction in ESI drops, even before shrapnel-fest.