What's with the new obsessions for ports and HD remakes?

Like /u/ReturntoFlesh84 said, it isn't new and have been around for ages.

Like... why wouldn't you want a NEW Smash or Mario Kart or whatever?

This is actually pretty simple. Ignoring possible things like different developers working on it, a lot of it has to do with a couple of key points.

The first is price, which makes sense when you think about it. While every game doesn't become rare, some do and ports give us an affordable option to play it legally. This is best seen with Earthbound, which seems to be $180~ incomplete on eBay. Obviously it would be much better to just pay $10~ on the Switch and have it digitally, on the go and all that.

In addition to that, space also plays a role. I have a lot of older games I love to play, be it Sonic the Hedgehog or Super Mario Bros., but the effort needed to hook up old consoles or space required to keep them hooked up isn't as valuable as just paying $5 to have it on something else.

Another is missing out on a previous console. It goes without saying that a LOT of people never experienced many of the titles on the Wii U, so it would be awesome to see Bayonetta 2, Pikmin 3 and more come over.

The final big one is discussion. "What new game would you love to see" is very bland and quickly leads to wish fulfillment. With something that exists, the confines are much smaller and it's easier to talk about. Saying I want to see a port of Bayonetta 2 can lead to a discussion about how nice it is or why people need to experience instead of the usual things like Metroid Prime 4. I'm not saying this doesn't also get into the usual things, but at least it has more discussion points.