Some games are initially overlooked or panned, only to become well regarded years later. But what about the opposite, when games are initially acclaimed and popular, only to be forgotten and/or panned years later?

Any interesting examples you can think of? And why do you think those games had these kinds of fates?

Twilight Princess and Skward Sword.

At the time of their release they were heralded as GOAT status.

Now not so much...

Every sports game from EA.

Here are a few examples:

• Battle Arena Toshinden - Back in 1995, this was considered a revolutionary game, promoted as the PlayStation's "Saturn Killer" (referencing Virtua Fighter). Nowadays, the game is practically forgotten, with conversation surrounding fighting games of the mid-to-late 90's focusing on Tekken, Soul Edge, Dead or Alive, Street Fighter, and SNK's lineup.
• Grand Theft Auto IV - This is one of the top rated games of all time, with a Metascore of 98 and 25 million sales. But nowadays, it's overshadowed by the PS2 era trilogy and especially GTA5.
• Metal Gear (NES) - Though largely regarded as a bastardized version of the original Metal Gear nowadays, this entry was widely regarded through the 90's, landing on Nintendo Power's and EGM's Top 100 Games of All Time lists.

Critics loved the Sonic Adventure games and were much more critical of their GameCube ports. Not so sure about players in general. I think the hype ran out for the critics or they thought the ports needed more.
Skyward Sword still mostly gets a positive reception but was super acclaimed at launch only to get a lot of flack the following years and some flack for the Switch remaster as well.
Super Smash Bros. is a weird case with two of its games. Brawl and Wii U got near universal acclaim at launch. But some people (namely a vocal minority) trashed Brawl for tripping and its slower speed, among other things. The tripping I can't justify ever being in the game, but the slower speed isn't big deal.
Wii U is getting a lot of flak for a Smash game in recent years with even one video calling it "Smash Without Substance". And when you look at most polls of people's favorite Smash, Wii U consistently ranks below Melee, Brawl, and Ultimate. It sometimes even ranks lower than 3DS or the original. I swear people only prefer Brawl over Wii U for Subspace Emissary. Because there's almost no other reason I could fathom.

Dragon Age: Inquisition and Overwatch come to mind. Both GOTY winners in their respective years that their love has dwindled in recent years.

Not sure about DA:I, maybe had something to do with Witcher 3 releasing not too long afterwards, but Overwatch was completely self-inflicted by Blizzard. Terrible choice after terrible choice that ruined all the goodwill they had built up in that first year.

I prefer basicly everything about Brawl over Wii U, the modes, the roster, UI, music ofc. The difference is subtle ofc in most cases, and Smash Wii U is still my favorite game on Wii U, but it falls in an awkard place between Brawl and Ultimate that I vastly prefer.

As for the main topic a lot of games that went Live Service post launch probably fit the bill.

Bioshock Infinite.

Heavily anticipated and praised on release, now largely ignored.

The IP in general went from being one of the signature IPe of the 7th gen to just sputtering out. 

Braid was another title that was praised to hell and back. Jonathan Blow was hailed as a genius. The much delayed remaster bombed badly enough that Blow was vocally upset about it. So many artsy plarformers like Celeste came along and they still have a loyal following.

Can't argue against what you said about OW but for DA:I, I'm not sure many do think ill of it. It won game of the year as the best game of that year, it a fantastic game but most years we have something special, some multiple. In 2014, did we? We had good games, just nothing that made a stamp.

Now, I am bias, as DA:I is one of my favourite games ever so take what I've said here as you will but I will say, after the recent entry in the series, I bet you there is a dang sight more people playing DA:I and thinking "Man, this was good."