This isn't anything new though. How many different platforms has Super Mario Brothers been playable on? Or Sonic 2?
The best games of every generation get brought to the next. Whether it's older stuff like Super Mario All Stars or the various Sega Ages and Classic collections. Most great PS1 and PS2 games saw release on the PS3, either digitally or in various physical collections. Tons of PS3 games have been re-released on PS4. Despite no backwards compatibility, there's only a few PS3 exclusive titles left stuck on that platform. I don't even know how many WiiU games are left that have not been ported to switch yet: that might be in the single-digits.
I don't see how Skyrim is much different, but for some reason the Internet loves to hate it Skyrim and Bethesda in particular. Don't get me wrong: they're a giant soulless corporation. But there's so many other corporations that have had way more consumer-unfriendly practices. Re-releasing a game on multiple platforms with new content added, usually at a pretty good price, just seems consumer friendly to me.