Honestly after seeing so many different people complaining about the same thing, let me give you a bit of my perspective with quite a popular game right now: Destiny 2.
I played Destiny a lot. When the beta for D2 came out for PC, I played at 60 fps for the first time and was the first in line to say I wouldn't go back to the capped 30 fps console version. Well tell you what: I did. And because the game is good in the end it doesn't matter much.
My point is: DOOM is an awesome game too. And If I can get used to 60 fps in Destiny 2 and 30 fps again after, I dont see why it would be any different in DOOM. It's a portable version. I for one am super happy that I'll be able to play a decent looking version of an awesome game anywhere I want.
I'd be more worried about the online infrastructure for the online multiplayer than anything else if I am to worry about anything at all.
Destiny 1 and 2 were both mainly designed for 30 fps. From the floaty jumps, slow run animations and what not.
Shooting is faster , and controls are responsive more in 60fps, but certain things like animations, and what not were all designed to look and be played out in a 30fps environment.
Doom has mechanics that actually revolve around the speed of the frame rate. From what I've seen of the switch version it looks like certain things have been sped up to compensate for 30fps.
I wonder if animations are shorter as to make the game flow better when in a hectic fight using a power up that makes you stronger or run super fast.
But in any case Doom was meant to be super fast paced, especially with doing visceral combo's, using power up orbs to actually even shoot/kill faster.
That all now has to be compensated somehow in it's timings, animation delay's.
I would rather they find a way to either render the game differently to accomodate switch hardware, and take a hit on res so they could achieve 60fps.
Running at 30fps to me kills what makes doom so great. And that's coming from someone who played it on both PS4 and PC.
Maybe they tried and it looked like crap???
I know people want sacrifices but if the game looked like dogshit at 60 FPS, it's not going to be worth it.
More than likely they have not had a lot of time developing for switch. They could have taken more time to maybe rework the engine more for tegra style chip switch has, and maybe write a more customized api, and renderer to help offset graphical impact on the processing so with a low res they would be able to achieve 60fps.
Gameplay means everything, and Doom is about fast paced in your face action that requires lightening reaction when in later fights during hell sections and beyond.