Well you said it yourself, which is likely a big part of the problem. Nin fans are tired of tests, and devs/pubs are probably tired of inferior hardware, among other things. As long as the hardware situation remains, the 'test method' will likely remain the norm. Unless maybe more handheld/hybrid devices start showing up, especially from competitors. 

GTAV was also the very end of 7th gen and pushed those consoles. My bro's 360 would take off like a PS4 when playing and coincidentally it ended up RROD'ing after a few months of only GTAV sessions. How easily Switch could handle that is questionable, even with downgrades. 

The Nin crowd is also known for buying the 'same old thing' over and over. Kinda like buying Fifa or Madden every single year. It's not always like that exactly but that's a general view. So if you're a 3rd party, why not bring old games to newer Switch devices eventually instead of the existing hardware? On one hand it does suck, on the other, it's certainly better than nothing.

Crysis 2 and 3 were more demanding on PS3/360 than GTA5, and Switch runs those with ease, with significant upgrades.

Crysis 2&3 aren't open world though are they?

Witcher 3 and Dying Light are, and are a generation ahead of GTA5 on PS3/360, and run on Switch.

Switch is significantly more capable than PS3/360, running their version of GTA5 on it shouldn't pose a problem.

You have a point with those examples.

"running their version of GTA5 on it wouldn't trouble a competent dev."

This is the kinda thing that put's most people off and doesn't help, especially if they have the capability. It just makes things worse. Only on the rarest of occasions will it move someone to 'prove you wrong'.

I edited my comment to be reword that part, as yeah, probably not helpful. 

It's better to show you learned something, but you do have the ability to undo the past here, sort of.

All Nin fans can do is voice their opinion in an appropriate manner and hope, while also following through with their wallets. Being snarky and demanding isn't the right way to go about things in general, and especially when you're dealing with giants of any kind.

The trilogy is a good sign though, yet no guarantee.

Personally I'm not even a fan of GTA; if I wanted to play it I could easily do on my PS3 or 360. I was only ever talking about it as a missed opportunity to score some easy extra sales, being one of the most popular games ever on what's soon to be one of the most popular systems ever and all that. Given we've seen everything from Skyrim to Assassin's Creed to Witcher 3 pop up on Switch, GTA5 has always just seemed a strange omission.

Well that's besides the point. The mindset in general is what matters and that's not a position only you hold. It in a way speaks for many, even if that's not what was intended.

Large entities do as they please. To T2 and R*, porting GTAV likely is at the bottom of the list of priorities. Focusing more on GTAV Online and GTA6 is probably more beneficial to them. Who knows, heck, they may plan to go above and beyond with GTA6 and do everything they can to make sure it's playable on Switch 2, on day 1. Would Nin gamers rather have that, or GTAV on Switch soon instead, if they had the choice?

It's not an either/or thing. There's nothing stopping them doing both. Sometimes companies, even the big successful ones, just make bad calls.