Screen Resolution - Pixel Density

Very likely due to the fact that the screen is different from your average LCD.  Aside from the transflective nature of the screen, it also has MIP (memory in pixel) technology.. basically,  each pixels stores its last state so that the screen redraw less (only changes trigger an update). I imagine that the MIP technology,  currently,  requires larger pixels than traditional LCD screens; so while Garmin was able to fit a larger screen, it will take more work to shrink the pixels themselves..

It is also possible that the lower DPi helps them squeeze out the battery life they do (these things have the power of other smart watches, but easily last 3-5x as long between charges..).

First of all, every Fenix since 3 has had the same pixel density. That said, I agree with your point that they really need to get a ‘retina’ (using Apple terminology for not being able to see pixels at standard operating distance) level pixel density. Here’s an example of a 1.3” (same as F6) round MIP display with 320x320: https://www.j-display.com/english/product/reflective.html

See round one at bottom of page. This was just first google hit, I’m sure there are others

The problem is,  how much extra power is required to utilize that display. All that extra real estate comes at a cost, in both processing power and memory.  I am sure they could do it.. but I would suspect that battery life would start dipping into just a few days (especially if rendering intensive maps and graphics. 

Now, if we could have a 320 display for the same or better life as we already get, I'm all for it. But right now, the screen is good enough that I prefer the strong battery life.

The just announced Garmin Venu:

1.2" display, 390x390 AMOLED display

https://www.garmin.com/en-US/venu/

Yes and look at the battery life. I think that is the problem that Garmin is waiting and is looking for a solution. And the new Fenix 6 Solar could be that solution. So maybe on a new Fenix  7?

And yeah, I'm using a stryd and was hoping for a native field for Power. There is also no Stryd support at the moment.

Mayby Garmin want to create this native field for Power with a software update in the future?

With this battery life spec, I'm not interested:

AMOLED display and up to 5-day battery life in smartwatch mode; up to 6 hours in GPS mode with music

For me, and a few others based on sales of the Fenix line, the screen is one of the reasons i bought the watch.  I like the MIP screen they use, i like that it is always on (like a real watch), and that it looks amazing in direct sunlight, unlike Samsung/Apple (this is an outdoor/fitness watch), and that it doesn't suddenly go super bright every time i move my wrist (i see these in movie theaters, and know people that wont wear them when they sleep because it wakes them up).... not to mention the amazing battery life, changing to Amoled/LCD will drastically reduce battery life, and a device like this that only has a few days between charges makes no sense to me.

Extra pixels won’t be a significant draw as long as the screen technology is the same. I’d be happy with a crisper version of the current screen tech (vs going with AMOLED like Venu)

That's 320x300 pixels, so it's round but the bottom part is cut. Actually, I think that's the display module used in Suunto and some other watches. Additionally, maybe Garmin doesn't bother that display module due to its being not completely round as many analogue watchfaces on the CIQ store would be sh*t on that screen and Garmin likes the round screen characteristic.

Also Garmin isn't a display module producer itself. So it's using the displays on the market. Maybe there aren't a lot of producers producing displas with higher resolutions to choose from. Garmin used one of the modules on this JDI page on Fenix 3 and 5 and probably the other on F5X. But there are different resolutions which aren't on JDI pages, so I don't know who produces them.

Ah, I didn’t catch the “flat tire” shape - agree, would not want that. Still, given this was just the first search result, I’m sure there are options out there (or Garmin probably has enough market power to have a supplier make one for them)